Particle Discrimination in TeO Bolometers using Light Detectors read out by
Particle Discrimination in TeO2 Bolometers using Light Detectors read out by
Transition Edge Sensors
K. Schäffner,1, ∗ G. Angloher,2 F. Bellini,3, 4 N. Casali,1, 5 F. Ferroni,3, 4 D. Hauff,2 N. Nagorny,1
L. Pattavina,1 F. Petricca,2 S. Pirro,1 F. Pröbst,2 F. Reindl,2 W. Seidel,2 and R. Strauss2
1
arXiv:1411.2562v1 [physics.ins-det] 10 Nov 2014
INFN - Laboratori Nazionali del Gran Sasso, Assergi (AQ) I-67010 - Italy
2
Max-Planck-Institut für Physik, D-80805 München, Germany
3
Dipartimento di Fisica - Università di Roma La Sapienza, I-00185 Roma - Italy
4
INFN - Sezione di Roma I, I-00185 Roma - Italy
5
Dipartimento di Scienze Fisiche e Chimiche - Università degli studi dell’Aquila, I-67100 Coppito (AQ) - Italy
An active discrimination of the dominant α-background is the prerequisite for future DBD experiments based on TeO2 bolometers. We investigate such α-particle rejection in cryogenic TeO2
bolometers by the detection of Cherenkov light. For a setup consisting of a large TeO2 crystal
(285 g) and a separate cryogenic light detector, both read out by transition edge sensors at around
10 mK, we obtain an event-by-event identification of e/γ- and α-events. In the energy interval ranging from 2400 keV to 2800 keV and covering the Q-value of 130 Te a discrimination power of 3.7 could
be demonstrated.
I.
INTRODUCTION
The postulation of the neutrino in 1930 by W. Pauli
was followed by many decades of intensive experimental
investigations, though still today important properties of
this particle are unknown. Oscillation experiments have
confirmed that the three families of neutrinos mix and
that at least two of them have a finite mass. However,
information on the absolute mass scale, the ordering of
these masses, charge conjugation properties and lepton
number conservation is still missing.
In the case that neutrinos are Majorana particles [1],
which implies the presence of physics beyond the Standard Model of particle physics, an extremely rare process should be observable, namely the so-called Neutrinoless Double Beta Decay (0νDBD) [2]: in a 0νDBD the
mother nucleus decays by the simultaneous emission of
two beta-particles only. As no neutrinos are emitted, the
full energy of the decay, the Q-value, is shared between
the two electrons. The evidence of 0νDBD would prove
that neutrinos are their own anti-particles and that lepton number is not conserved. Also, constraints would be
set on the mass scale of the neutrinos.
Numerous experiments are searching for this process
with the distinctive signature of a monochromatic line at
the Q-value of the decay - the combined energy of the
two simultaneously emitted electrons.
Low temperature bolometers are ideal detectors for
such surveys: crystals can be grown with a variety of
interesting DBD-emitters, and multi-kg detectors [3] can
be operated with excellent energy resolution (1-2%) at
the Q-value [4].
Up to now, low temperature bolometers searching for
0νDBD were mainly using TeO2 crystals [4, 5], which
show very good mechanical and thermal properties [6],
∗
corresponding author:karoline.schaeffner@lngs.infn.it
have a very large natural isotopic abundance of the candidate isotope 130 Te (34.2% [7]) and, most importantly,
are produced at industrial scale.
At present, radioactive surface contamination is the
key-issue [8, 9] that may limit the sensitivity of tonne
scale experiments like CUORE [10]: α-particles can loose
a fraction of their initial energy while passing through
the bulk material before interacting in the bolometer.
Such, so-called degraded α-particles show a flat energy
spectrum ranging from the Q-value of the decay (several
MeV) down to threshold energy, thereby possibly creating
background within the region of interest for 0νDBD [11].
For next-generation bolometric DBD experiments beyond CUORE [12], the only way to further reduce this
α-background is to actively identify the interacting particles. In case of non-scintillating crystals like TeO2
this discrimination could be obtained measuring the
Cherenkov light emitted by electrons as suggested in
[13]. Alpha-particles of few MeV have energies below
the threshold for the creation of Cherenkov light. Since
the expected light signal of electrons is O(100 eV) [13],
light detectors with excellent performance should be employed.
The first published measurement on the detection of
Cherenkov light in this context was carried out on a 116 g
TeO2 crystal demonstrating that α-particles can be discriminated [14]. Very recently an event-by-event discrimination was obtained with a very small TeO2 bolometer
based on a 23 g crystal [15]. Measurements on a large
crystal (750 g) demonstrate that difficulties may substantially increase with crystal size and light detectors with
a threshold as low as some 10 eV are required [16].
In this work we report the results from a measurement
of the Cherenkov light emitted by a large 285 g TeO2
bolometer. The light absorber is read out by a Transition Edge Sensor (TES) of the same type as used in the
CRESST dark matter search [17], proving for the first
time that an effective event-by-event discrimination can
be achieved also on large mass crystals.
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–5
The New Muon g-2 experiment at Fermilab
arXiv:1411.2555v1 [physics.ins-det] 10 Nov 2014
Graziano Venanzoni,
on behalf of the Fermilab E989 collaboration
Laboratori Nazionali di Frascati dell’INFN, Frascati, Italy
Abstract
There is a long standing discrepancy between the Standard Model prediction for the muon g-2 and the value measured by the Brookhaven E821 Experiment. At present the discrepancy stands at about three standard deviations,
with a comparable accuracy between experiment and theory. Two new proposals – at Fermilab and J-PARC – plan
to improve the experimental uncertainty by a factor of 4, and it is expected that there will be a significant reduction
in the uncertainty of the Standard Model prediction. I will review the status of the planned experiment at Fermilab,
E989, which will analyse 21 times more muons than the BNL experiment and discuss how the systematic uncertainty
will be reduced by a factor of 3 such that a precision of 0.14 ppm can be achieved.
1. Introduction
The muon anomaly aµ = (g − 2)/2 is a low-energy
observable, which can be both measured and computed
to high precision [1, 2]. Therefore it provides an
important test of the Standard Model (SM) and it is
a sensitive search for new physics [3]. Since the first
precision measurement of aµ from the E821 experiment
at BNL in 2001 [4], there has been a discrepancy
between its experimental value and the SM prediction.
The significance of this discrepancy has been slowly
growing due to reductions in the theory uncertainty.
Figure 1 (taken from [5]) shows a recent comparison
of the SM predictions of different groups and the
BNL measurement for aµ . The aµ determinations of
the different groups are in very good agreement and
show a consistent ≈ 3 σ discrepancy [5, 6, 7], despite
many recent iterations in the SM calculation. It should
be noted that with the final E821 measurement and
advances in the theoretical SM calculation that both the
theory and experiment uncertainties have been reduced
by more than a factor two in the last ten years [8]. The
Email address: graziano.venanzoni@lnf.infn.it
(Graziano Venanzoni)
accuracy of the theoretical prediction (δaTH
µ , between 5
and 6 ×10−10 ) is limited by the strong interaction effects
which cannot be computed perturbatively at low energies. The leading-order hadronic vacuum polarization
contribution, aHLO
, gives the main uncertainty (between
µ
−10
4 and 5 ×10 ). It can be related by a dispersion
integral to the measured hadronic cross sections, and
it is known with a fractional accuracy of 0.7%, i.e.
to about 0.4 ppm. The O(α3 ) hadronic light-by-light
contribution, aHLbL
, is the second dominant error in the
µ
theoretical evaluation. It cannot at present be determined from data, and relies on using specific models.
Although its value is almost two orders of magnitude
smaller than aHLO
, it is much worse known (with a
µ
fractional error of the order of 30%) and therefore it
still give a significant contribution to δaTH
µ (between 2.5
and 4 ×10−10 ).
From the experimental side, the error achieved by the
BNL E821 experiment is δaEXP
= 6.3 × 10−10 (0.54
µ
ppm) [9]. This impressive result is still limited by the
statistical errors, and a new experiment, E989 [10], to
measure the muon anomaly to a precision of 1.6 × 10−10
(0.14 ppm) is under construction at Fermilab. If the central value remains unchanged, then the statistical signif-
Preprint typeset in JINST style - HYPER VERSION
arXiv:1411.2466v1 [physics.ins-det] 10 Nov 2014
The Resistive-WELL detector: a compact
spark-protected single amplification-stage MPGD
G. Bencivennia∗, R. De Oliveirab , G. Morelloa , M. Poli Lenera
a Laboratori
Nazionali di Frascati dell’INFN
Frascati, Italy
b CERN, Meyrin, Switzerland
E-mail: giovanni.bencivenni@lnf.infn.it
A BSTRACT: In this work we present a novel idea for a compact spark-protected single amplification stage Micro-Pattern Gas Detector (MPGD). The detector amplification stage, realized with a
structure very similar to a GEM foil, is embedded through a resistive layer in the readout board.
A cathode electrode, defining the gas conversion/drift gap, completes the detector mechanics. The
new structure, that we call Resistive-WELL (R-WELL), has some characteristics in common with
previous MPGDs, such as C.A.T. and WELL, developed more than ten years ago. The prototype
object of the present study has been realized in the 2009 by TE-MPE-EM Workshop at CERN. The
new architecture is a very compact MPGD, robust against discharges and exhibiting a large gain
(∼6×103 ), simple to construct and easy for engineering and then suitable for large area tracking
devices as well as huge calorimetric apparata.
K EYWORDS : MPGD; Tracking and position sensitive detectors; Hadron Digital Calorimeter.
∗ Corresponding
author.
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–8
The NEXT experiment
J.J. Gomez-Cadenas∗
arXiv:1411.2433v1 [physics.ins-det] 10 Nov 2014
Instituto de F´ısica Corpuscular (IFIC), CSIC & Universidad de Valencia
Abstract
NEXT (Neutrino Experiment with a Xenon TPC) is an experiment to search neutrinoless double beta decay processes (ββ0ν). The isotope chosen by NEXT is 136 Xe. The NEXT technology is based in the use of time projection
chambers operating at a typical pressure of 15 bar and using electroluminescence to amplify the signal (HPXe). The
main advantages of the experimental technique are: a) excellent energy resolution; b) the ability to reconstruct the
trajectory of the two electrons emitted in the decays, a unique feature of the HPXe which further contributes to the suppression of backgrounds; c) scalability to large masses; and d) the possibility to reduce the background to negligible
levels thanks to the barium tagging technology (BaTa).
The NEXT roadmap was designed in four stages: i) Demonstration of the HPXe technology with prototypes deploying a mass of natural xenon in the range of 1 kg; ii) Characterisation of the backgrounds to the ββ0ν signal and
measurement of the ββ2ν signal with the NEW detector, deploying 10 kg of enriched xenon and operating at the LSC;
iii) Search for ββ0ν decays with the NEXT-100 detector, which deploys 100 kg of enriched xenon; iv) Search for ββ0ν
decays with the BEXT detector, which will deploy masses in the range of the ton and will introduce two additional
handles, only possible in a HPXe: a) A magnetic field, capable of further enhancing the topological signal of NEXT;
and b) barium-tagging (a technique pioneered by the EXO experiment which is also accessible to NEXT).
The first stage of NEXT has been successfully completed during the period 2009-2013. The prototypes NEXTDEMO (IFIC) and NEXT-DBDM (Berkeley) were built and operated for more than two years. These apparatuses
have demonstrated the main features of the technology. The experiment is currently developing its second phase. The
NEW detector is being constructed during 2014 and will operate in the LSC during 2015. The NEXT-100 detector
will be built and commissioned during 2016 and 2017 and will start data taking in 2018. NEXT-100 could discover
ββ0ν processes if the period of the decay is equal or less than 6 × 1025 year. The fourth phase of the experiment
(BEXT) could start in 2020.
Keywords: Majorana neutrinos, High Pressure Xenon chamber (HPXe), Double beta decay, NEXT,
Electroluminescence
1. Introduction
Neutrinos, unlike the other fermions of the Standard
Model of particle physics, could be Majorana particles,
∗ On
behalf of the NEXT collaboration
Email address: gomez@mail.cern.ch (J.J. Gomez-Cadenas )
URL: http://next.ific.uv.es/next/ (J.J.
Gomez-Cadenas )
that is, indistinguishable from their antiparticles. The
existence of Majorana neutrinos would have profound
implications in particle physics and cosmology.
If neutrinos are Majorana particles, there must exist
a new scale of physics (at a level inversely proportional
to the neutrino masses) that characterises the underlying dynamics beyond the Standard Model. The existence of such a new scale provides the simplest expla-
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–3
Optimization of neutrino fluxes for future long baseline neutrino oscillation
experiments
arXiv:1411.2418v1 [physics.ins-det] 10 Nov 2014
M. Calviania , S. di Luiseb , V. Galymovc , P. Veltena
a CERN, Geneva, Switzerland
Z¨urich, Institue for Particle Physics, Switzerland
c Institut de Physique Nucl´
eaire de Lyon, Villeurbanne, France
b ETH
Abstract
One of the main goals of the Long Baseline Neutrino Oscillation experiment (LBNO) experiment is to study the
L/E behaviour of the electron neutrino appearance probability in order to determine the unknown phase δCP . In the
standard neutrino 3-flavour mixing paradigm, this parameter encapsulates a possibility of a CP violation in the lepton
sector that in turn could help explain the matter-antimatter asymmetry in the universe. In LBNO, the measurement of
δCP would rely on the observation of the electron appearance probability in a broad energy range covering the 1 st and
2nd maxima of the oscillation probability. An optimization of the energy spectrum of the neutrino beam is necessary
to find the best coverage of the neutrino energies of interest. This in general is a complex task that requires exploring
a large parameter space describing hadron target and beamline focusing elements. In this paper we will present a
numerical approach of finding a solution to this difficult optimization problem often encountered in design of modern
neutrino beamlines and we will show the improved LBNO sensitivity to the presence of the leptonic CP violation
attained after the neutrino beam optimization.
Keywords:
neutrino beam simulation, beam optics, magnetic horn, numerical optimization, genetic algorithms, machine
learning, long baseline neutrino oscillations, leptonic CP violation
LBNO will utilize a neutrino beam conventionally
produced with a high intensity proton beam impinging
on a target. The proton beam will be delivered at the
CERN accelerator complex. Two options are foreseen
for the two successive phases of the experiment. In the
first phase, an upgraded SPS will deliver 400 GeV protons at about 700 kW beam power. The expected integrated yearly exposure is about 1.0 × 1020 protons on
target (POT). In the second phase, a primary beam is
foreseen to be provided by a high power PS (HPPS) facility which will deliver a 50 GeV 2 MW proton beam
and an integrated yearly exposure of about 3.5 × 1021
POT.
A model of the neutrino beamline has been developed
in FLUKA[4] for the calculation of the neutrino flux. In
the model, the hadron production target is described as
solid graphite cylinder. The focusing optics consists of
two aluminum horns. The target is fully inserted into
the first horn in order to maximize the collection of the
low energy pions which contribute to the neutrino flux
below 2 GeV (around the 2nd oscillation maximum). At
this stage no support system for the target and horns has
been modeled and the components are simply placed
in an empty environment representing the target station
hall. The decay tunnel, modeled as a cylinder 300 m
long and 3 m in diameter is located 30 m downstream of
the target. A hadron beam stop (beam dump) is placed
at the end of the decay volume. The geometry of the
1 st horn adopted in this study differs significantly from
simple parabolic horn considered in the LBNO expression of interest [1]. The new design aims to improve
collection of the low energy secondaries that exit the
Assessing the Feasibility of Interrogating Nuclear Waste Storage Silos using Cosmic-ray
Muons
F. Ambrosinoa,b, L. Bonechic , L. Cimminoa,b, R. D’Alessandroc,d, D. G. Irelande, R. B. Kaisere , D. F. Mahone, N. Morif,c , P. Nolib ,
G. Saracinoa,b, C. Shearerg , L. Vilianic,d , G. Yange
a Department
of Physics, University of Naples Federico II, Naples , Italy
sezione di Napoli, I-80126 Naples, Italy
c INFN, sezione di Firenze, I-50019 Sesto Fiorentino, Florence, Italy
d Department of Physics and Astronomy, University of Florence, I-50019 Sesto Fiorentino, Florence, Italy
e SUPA, School Of Physics & Astronomy, University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, Scotland, UK
f Centro Siciliano di Fisica Nucleare e Struttura della Materia (CSFNSM), I-95125 Catania, Italy
g National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG, England, UK
arXiv:1411.2382v1 [physics.ins-det] 10 Nov 2014
b INFN,
Abstract
Muon radiography is a fast growing field in applied scientific research. In recent years, many detector technologies and imaging techniques using the Coulomb scattering and absorption properties of cosmic-ray muons have been developed for the nondestructive assay of various structures across a wide range of applications. This work presents the first results that assess the
feasibility of using muon radiography to interrogate waste silos within the UK Nuclear Industry. Two such approaches, using
different techniques that exploit each of these properties, have previously been published, and show promising results from both
simulation and experimental data for the detection of shielded high-Z materials and density variations from volcanic assay. Both
detector systems used are based on scintillator and photomultiplier technologies.
Results from dedicated simulation studies using both these technologies and image reconstruction techniques are presented for
an intermediate-sized legacy nuclear waste storage facility filled with concrete and an array of uranium samples. Both results
highlight the potential to identify uranium objects of varying thicknesses greater than 5 cm within real-time durations of several
weeks. Increased contributions from Coulomb scattering within the concrete matrix of the structure hinder the ability of both
approaches to resolve similar objects of 2 cm dimensions even with increased statistics. These results are all dependent on both the
position of the objects within the facility and the locations of the detectors. Results for differing thicknesses of concrete, which
reflect the unknown composition of the structures under interrogation, are also presented alongside studies performed for a series
of data collection durations. It is anticipated that with further research, muon radiography in one, or both of these forms, will play
a key role in future industrial applications within the UK Nuclear Industry.
Keywords: Muon Radiography, Scintillator Detectors, Nuclear Waste
PACS: 96.50.S-, 29.40.Mc, 89.20.Bb
1. Introduction
When high-energy cosmic rays bombard the Earth’s atmosphere, highly-penetrating showers of muons are produced and
subsequently observed at sea level with a flux of approximately
one muon per square centimetre per minute. As charged particles, muons interact with matter primarily through ionising
interactions with atomic electrons and via Coulomb scattering from nuclei. Both of these mechanisms have been exploited in recent years within the field of muon radiography
(alternatively, muography) to probe the internal composition of
shielded and/or large structures that cannot be probed via conventional imaging techniques such as X-rays. Since the pioneering experiment by E. P. George measured the thickness of
the ice burden above the Guthega-Munyang tunnel in Australia
in the 1950s [1] and L. W. Alvarez conducted his search for hidden chambers in the Second Pyramid of Chephren in Egypt [2]
a decade later, there has been a wealth of wide-ranging appliPreprint submitted to arXiv
cations that have made use of cosmic-ray muons for imaging
purposes, such as in volcanology [3, 4, 5], nuclear contraband
detection for national security [6, 7] and in the characterisation
of legacy nuclear waste [8, 9, 10, 11].
Recent results presented in Refs. [12, 13] first investigated
the comparison between muon absorption (or transmission) and
Coulomb scattering techniques for the assay of the tsunamidamaged reactors at the stricken Fukushima-Daiichi facility in
Japan. For this particular scale of application, the scattering
approach provided better sensitivity to the core material and
potential voids within several weeks of simulated exposure to
cosmic-ray muons. Subsequent research applied this Coulomb
scattering technique to the experimental interrogation of the
AGN-201M test reactor at the University of New Mexico [14]
and the Toshiba Nuclear Critical Assembly reactor [15] to verify the potential of these image reconstruction techniques for an
application of this nature and scale.
The results presented in the current work are the first from
November 11, 2014
Transverse-momentum dependent parton distribution functions
beyond leading twist in quark models
C. Lorc´e,1, 2 B. Pasquini,3, 4 and P. Schweitzer5
arXiv:1411.2550v1 [hep-ph] 10 Nov 2014
1
SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025 USA
2
IFPA, AGO Department, Universit´e de Li`ege, Sart-Tilman, 4000 Li`ege, Belgium
3
Dipartimento di Fisica, Universit`
a degli Studi di Pavia, Pavia, Italy
4
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Pavia, Italy
5
Department of Physics, University of Connecticut, Storrs, CT 06269, USA
Higher-twist transverse momentum dependent parton distribution functions (TMDs) are a valuable probe of the quark-gluon dynamics in the nucleon, and play a vital role for the explanation of
sizable azimuthal asymmetries in hadron production from unpolarized and polarized deep-inelastic
lepton-nucleon scattering observed in experiments at CERN, DESY and Jefferson Lab. The associated observables are challenging to interpret, and still await a complete theoretical explanation,
which makes guidance from models valuable. In this work we establish the formalism to describe
unpolarized higher-twist TMDs in the light-front framework based on a Fock-space expansion of the
nucleon state in terms of free on-shell parton states. We derive general expressions and present numerical results in a practical realization of this picture provided by the light-front constituent quark
model. We review several other popular quark model approaches including free quark ensemble,
bag, spectator and chiral quark-soliton model. We discuss how higher-twist TMDs are described in
these models, and obtain results for several TMDs not discussed previously in literature. This study
contributes to the understanding of non-perturbative properties of subleading twist TMDs. The results from the light-front constituent quark model are also compared to available phenomenological
information, showing a satisfactory agreement.
PACS numbers: 12.39.Ki, 13.60.Hb, 13.85.Qk
Keywords: quark-gluon structure, higher twist, transverse momentum dependent distribution functions
I.
INTRODUCTION
Azimuthal (spin) asymmetries in semi-inclusive deep-inelastic scattering (SIDIS) due to transverse parton momenta [1, 2] can be classified as unsuppressed leading-twist (twist-2) and power-suppressed subleading-twist (twist-3)
effects in the sense of the “working twist-definition” of Ref. [3]. The theoretical description of leading-twist effects is
cleaner, and clear experimental evidence is available, see [4–6] for reviews. However, the first measurements of such
asymmetries in SIDIS in unpolarized case by EMC [7, 8] or with longitudinally polarized targets by HERMES [9–12]
unexpectedly revealed larger effects at twist-3 level than at twist-2 in the fixed-target kinematics of these experiments.
Further data on twist-3 SIDIS effects (including preliminary results) was reported in Refs. [13–21].
SIDIS is a rich source of information on the nucleon structure including subleading-twist effects. However, in a
tree-level factorization approach, twist-3 SIDIS observables receive 4 (or 6) contributions due to twist-3 (or twist-2)
transverse momentum dependent parton distribution functions (TMDs) convoluted with twist-2 (or twist-3) transverse
momentum dependent fragmentation functions [22]. This makes the theoretical interpretation of data challenging,
and motivates model studies to help to clarify the underlying physics. The important impact of model studies for the
understanding of TMDs was reviewed in [23]. Model calculations also indicate that the status of TMD factorization
in SIDIS beyond leading twist is not yet fully clarified [24]. Information on collinear twist-3 parton distribution
functions is limited to gTq (x) accessed in polarized DIS, see [25] for an overview. The interference fragmentation
function approach based on collinear factorization offers a way to access further twist-3 parton distribution functions
in a collinear factorization [26]. A first extraction of one of these functions, namely eq (x), using this framework was
recently reported in Ref. [27].
Higher-twist TMDs can in general be decomposed in contributions from leading-twist, current quark mass terms
and pure interaction-dependent (“tilde”) terms. This is accomplished by employing equations of motion (EOM) and
reveals that tilde-terms are not parton densities but quark-gluon correlation functions. Neglecting the tilde- and mass
terms is sometimes referred to as Wandzura-Wilczek approximation [28]. This step can be helpful in phenomenology
to disentangle the many contributions to twist-3 SIDIS observables [29–32], and can in certain cases be a numerically
useful approximation [25, 33]. But it removes the richness of the largely unexplored but attractive non-perturbative
physics of quark-gluon correlations. Precisely this is an important motivation to study subleading-twist effects [34, 35].
Higher-twist TMDs and parton distribution functions of quarks are expressed in terms of hadronic matrix elements
of bilinear quark-field correlators of the type hh|ψ(0)Γψ(z)|hi, which makes them amenable to studies in quark
models [36], defined in the following as models without explicit gauge-field degrees of freedom. Quark models with
interactions allow one, in principle, to model also the interaction-dependent tilde-terms. Quark models have been
shown to give a useful description of leading-twist TMDs and related SIDIS observables, provided one applies them
carefully within their range of applicability. Much less is known about higher-twist TMDs, and important questions
Exploring Nucleon Structure with the Self-Organizing Maps Algorithm
Evan M. Askanazi,1, ∗ Katherine A. Holcomb,2, † and Simonetta Liuti1, 3, ‡
1
Department of Physics, University of Virginia, Charlottesville, VA 22901, USA.
2
University of Virginia Alliance for Computational Science and Engineering,
University of Virginia, Charlottesville, VA 22901, USA.
3
Laboratori Nazionali di Frascati, INFN, Frascati, Italy
We discuss the application of an alternative type of neural network, the Self-Organizing Map to
extract parton distribution functions from various hard scattering processes.
arXiv:1411.2487v1 [hep-ph] 10 Nov 2014
PACS numbers: 13.60.Hb, 13.40.Gp, 24.85.+p
I.
INTRODUCTION
Artificial Neural Networks (ANNs) are an algorithm model inspired by the human brain’s capacity to perform
the complex operations of learning, memorizing and generalizing. The goal of ANNs is, however, to solve objective
problems which are by far less complex relatively to the human brain capabilities. Their basic units are sets of nodes
that are defined as neurons because they can take sets of input parameters and either retain or communicate a signal
in a similar way to how signals propagate from one neuron to the other as the neurons get activated/fire. This
procedure is defined via learning algorithms. Its main success is in that it allows one to estimate non-linear functions
of input data.
ANNs consist of a set of initial data forming an input layer, a process by which the input data are evolved and
trained (hidden layers), and a resulting set of output data, or the output layer (Figure 1). Researchers currently utilize
ANNs in data visualization, function modeling and approximating values of functions, data processing, robotics and
control engineering. In the past twenty years ANNs have also established their role as a remarkable computational
tool in high energy, nuclear and computational physics analyses. Important applications have been developed, for
instance, as classification methods for off-line jet identification and tracking, on-line process control or event trigger
and mass reconstruction, and optimization techniques in e.g. track finding and classification [1].
Neural networks are used for modeling in these fields of physics because they can utilize the principle of learning
with regards to data sets and models. The learning can be supervised or unsupervised.
x1 Weights
x1 x2 x2 y x3 x3 x4 x4 Input Layer
Hidden Layer
Output Layer
Initial Data set
Winner node/Latent Variables
FIG. 1: Artificial neural networks based on supervised learning (left), and unsupervised learning (right).
∗ Electronic
address: ema9u@virginia.edu
address: kholcomb@virginia.edu
‡ Electronic address: sl4y@virginia.edu
† Electronic
IFIC/14-74
Instanton-mediated baryon number violation
arXiv:1411.2471v1 [hep-ph] 10 Nov 2014
in non-universal gauge extended models
´s† and P. Ruiz-Femen´ıa‡
J. Fuentes-Mart´ın∗ , J. Portole
Instituto de F´ısica Corpuscular, CSIC - Universitat de Val`encia,
Apt. Correus 22085, E-46071 Val`encia, Spain
Abstract
Instanton solutions of non-abelian Yang-Mills theories generate an effective action that
may induce lepton and baryon number violations, namely ∆B = ∆L = nf , being nf
the number of families coupled to the gauge group. In this article we study instanton
mediated processes in a SU (2)` ⊗ SU (2)h ⊗ U (1) extension of the Standard Model that
breaks universality by singularizing the third family. In the construction of the instanton
Green functions we account systematically for the inter-family mixing. This allows us to
use the experimental bounds on proton decay in order to constrain the gauge coupling
of SU (2)h . Tau lepton non-leptonic and radiative decays with ∆B = ∆L = 1 are also
analysed.
PACS : 11.30.Fs, 11.20.Hv, 12.60.Cn, 13.35.Dx
Keywords : Baryon Number Violation, Lepton Number Violation, Proton Decay, Tau Decays
∗
Email: Javier.Fuentes@ific.uv.es
Email: Jorge.Portoles@ific.uv.es
‡
Email: Pedro.Ruiz@ific.uv.es
†
arXiv:1411.2257v1 [hep-ph] 9 Nov 2014
The generalized BLM approach to fix
scale-dependence in QCD:
the current status of investigations
A L Kataev 1
1 Institute for Nuclear Research of the Academy of Sciences of Russia, Moscow 117312, Russia
E-mail: kataev@ms2.inr.ac.ru
Abstract. I present a brief review of the generalized Brodsky-Lepage-McKenzie (BLM)
approaches to fix the scale-dependence of the renormalization group (RG) invariant quantities
in QCD. At first, these approaches are based on the expansions of the coefficients of the
perturbative series for the RG-invariant quantities in the products of the coefficients βi of
the QCD β-function, which are evaluated in the MS-like schemes. As a next step all βi dependent terms are absorbed into the BLM-type scale(s) of the powers of the QCD couplings.
The difference between two existing formulations of the above mentioned generalizations based
on the seBLM approach and the Principle of Maximal Conformality (PMC) are clarified in
the case of the Bjorken polarized deep-inelastic scattering sum rule. Using the conformal
symmetry-based relations for the non-singlet coefficient functions of the Adler D-function and of
Bjp
Bjorken polarized deep-inelastic scattering sum rules CNS
(as ) the βi -dependent structure of the
Bjp
NNLO approximation for CNS (as ) is predicted in QCD with ngl -multiplet of gluino degrees of
freedom, which appear in SUSY extension of QCD. The importance of performing the analytical
Bjp
calculation of the N3 LO additional contributions of ngl gluino multiplet to CNS
(as ) for checking
the presented in the report NNLO prediction and for the studies of the possibility to determine
the discussed {β}-expansion pattern of this sum rule at the O(a4s )-level is emphasised.
1. Introduction
It is known that the results of perturbative calculations of the physical quantities, which obey
the RG equations (for the development of the RG method see e.g. [1, 2, 3]), depend on the choice
of the scale and scheme of the renormalization procedure. In the case of QCD this problem is
of particular importance. Indeed, calculations of the multiloop corrections to the observable
physical quantities and to the related RG- functions (namely, β-function and various anomalous
dimensions) are usually performed in the class of minimal subtractions (MS) schemes, and in the
MS -scheme [4], in particular. In this case, an error of the comparison of theoretical results with
experimental data is usually determined by varying the corresponding renormalization scale µ2
within the concrete interval, say µ2 /k ≤ µ2 ≤ kµ2 , where k is the conventionally chosen number,
i.e. k = 2 ÷ 4 (this convention was recently used recently in [5] ). As can be seen from this
work and from the studies of heavy flavour contributions to DIS sum rules [6], this interval for
k is indeed conventional. Say, the analysis of [6] motivates the choice of the following interval
for µ2 : m2q ≤ µ2 ≤ (6.5mq )2 , where mq are the c and b-quark pole masses. Note, that in the
process fitting the CCFR collaboration xF3 structure functions data for νN DIS [7] both ways of
On probing Higgs couplings in H → ZV decays
Tanmoy Modak∗ and Rahul Srivastava†
arXiv:1411.2210v1 [hep-ph] 9 Nov 2014
The Institute of Mathematical Sciences, Taramani, Chennai 600113, India
(Dated: November 11, 2014)
We analyze the possibility of probing Higgs couplings in the rare decays H → ZV , V being a
vector quarkonium state. These rare decays involve both gauge as well as the Yukawa sectors and
either of them can be potentially anomalous. Moreover, as both V and Z can decay into pair of
charged leptons, they provide experimentally clean channels and future LHC runs should observe
such decays. We discuss origin of all possible contributions and their relative strengths in H → ZV
process. We perform a model independent analysis and show how angular asymmetries can be used
for probing Higgs couplings in the rare decays, taking further decays of V and Z to pair of leptons
into account. The angular asymmetries can play a significant role in probing Higgs couplings to SM
particles in both gauge and Yukawa sectors.
I.
INTRODUCTION
The ATLAS and CMS collaborations at Large Hadron
Collider (LHC) have recently discovered a new bosonic
resonance of mass around 125 GeV [1–5]. Measuring its
coupling to different Standard Model (SM) particles and
establishing its nature are going to be leading aims of
future LHC runs. Although it is yet to be confirmed
as SM Higgs, in this paper we specify this resonance as
Higgs and denote it by H. Any deviations from its SM
nature should exhibit in its coupling to different particles.
Anomalous couplings of Higgs may come in both gauge
and Yukawa sectors. Establishing the nature of the Higgs
will require a precise measurement of its gauge as well as
Yukawa couplings. In future LHC runs the coupling of
Higgs to W, Z bosons will be measured in several different
channels such as H → ZZ ∗ → 4ℓ. However, measuring
its coupling to fermions as well as loop induced couplings
like HZγ are going to be relatively more challenging.
In this regard, several studies [6–27] have been directed
towards rare Higgs decays such as H → ZV ; V being a
vector quarkonium (J PC = 1−− ). Although the branching ratios are small, rare Higgs decays offer complimentary information about Higgs couplings [7] and can serve
as important probe of “New Physics” (NP). Besides, subsequent decays of Z and V into pair of leptons make them
experimentally clean channels. Moreover, the decay rates
are further enhanced by resonant production of V and
could be seen in high luminosity LHC runs or in future
colliders. Among rare Higgs decays, the decay to a vector
quarkonium (J/ψ, Υ) received considerable attention in
recent times. Refs. [8–10] have studied H → ZV process
with the aim to probe Higgs couplings and new physics.
There exist three different processes that contribute to
the H → ZV decay. Refs. [7, 8] calculate the decay rates
for H → ZV via H → Z ∗ Z with Z ∗ → V . Although
in SM the process H → Zγ ∗ → ZV is loop suppressed,
Ref. [10] shows that it can provide a significant contribution depending on the nature of the vector boson V .
∗
†
tanmoyy@imsc.res.in
rahuls@imsc.res.in
There exist a third contribution where H → ZV is produced via H → q q¯ → ZV and Ref. [9] studies this channel assuming anomalous coupling in Yukawa sector. As
any of the above three processes could be anomalous, in
this paper we perform a model independent analysis of
H → ZV decay without making any assumption on its
origin.
We first calculate the SM contribution of the three processes and their respective interferences to the H → ZV
decay. We also write down the most general HZV vertex
and derive corresponding angular asymmetries from it.
These asymmetries have been discussed in Ref. [28, 29]
in the context of H → ZZ ∗ → 4ℓ and also in Ref .[13]
to probe non standard Higss coupling via angular analysis. They provide powerful tools which can probe SM as
well as any anomalous contributions to the decay. Similar
asymmetry has also been discussed in Ref. [9] to measure
CP odd properties of Yukawa sector in H → ZV decays.
In our work we construct all possible asymmetries and
perform a case by case analysis discussing relative contributions of different diagrams and their consequences
on respective asymmetries.
The plan of the paper goes as follows. In section II we
compute the SM contributions of the three processes and
compare their relative strengths. Section III is devoted
to formalize the angular analysis and construction of angular asymmetries for H → ZV with further decays of V
and Z into pair of leptons. We also discuss how to probe
different Higgs coupling using these angular asymmetries.
In Section IV we conclude our results.
II. STANDARD MODEL CONTRIBUTION OF
DIFFERENT CHANNELS TO H → ZV PROCESS
We start our discussion by first estimating the relative strength of SM contribution of different channels to
the process H → ZV , where V is a vector quarkonium
(J P C = 1−− ). In particular we will focus on J/ψ(1S)
and Υ(1S) but our analysis is general and can be used
for any vector quarkonium. These decays receive contributions from three different diagrams as shown in Fig.1.
Some of these contributions have been individually stud-
HUPD1404
Precise Discussion on BaBar Asymmetry verifying Time Reversal
Asymmetry
Takuya Morozumi,∗ Hideaki Okane,† and Hiroyuki Umeeda‡
Graduate School of Science, Hiroshima University,
arXiv:1411.2104v1 [hep-ph] 8 Nov 2014
Higashi-Hiroshima, 739-8526, Japan
Abstract
BaBar collaboration announced that they observed time reversal (T) asymmetry through B
meson system. In the experiment, the event number of two distinctive processes, B− → B¯0 and
B¯0 → B− (− expresses CP value) is compared with each other. Event number difference of these
two processes is naively thought to be T-odd since they are related with flipping time direction.
In our study, BaBar asymmetry is written in terms of a general time-dependent structure. We
introduce parameters with definitively T-odd or T-even, in order to express the asymmetry. Using
our notation, one can find that BaBar asymmetry is not a precisely T-odd quantity, taking into
account indirect CP and CPT violation of neutral meson systems and wrong sign decay amplitudes.
Some combinations of the asymmetry enable one to extract parameters for wrong sign decays, CPT
violation, etc. We also study the reason why the T-even terms are allowed to contribute to the
asymmetry, and find that several conditions are needed for the asymmetry to be a T-odd quantity.
∗
†
‡
E-mail:morozumi@hiroshima-u.ac.jp
E-mail:hideaki-ookane@hiroshima-u.ac.jp
E-mail:umeeda@theo.phys.sci.hiroshima-u.ac.jp
1
EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)
arXiv:1411.2357v1 [hep-ex] 10 Nov 2014
CERN-PH-EP-2014-172
Submitted to: Physical Review Letters
Measurements of the Nuclear Modification Factor for Jets in
√
Pb+Pb Collisions at sNN = 2.76 TeV with the ATLAS Detector
The ATLAS Collaboration
Abstract
√
Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at sNN =
2.76 TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 pb−1
and 0.14 nb−1 , respectively. The jets are identified with the anti-kt algorithm with R = 0.4, and the
spectra are measured over the kinematic range of jet transverse momentum 32 < pT < 500 GeV, and
absolute rapidity |y| < 2.1 and as a function of collision centrality. The nuclear modification factor,
RAA , is evaluated and jets are found to be suppressed by approximately a factor of two in central
collisions compared to pp collisions. The RAA shows a slight increase with pT and no significant
variation with rapidity.
c 2014 CERN for the benefit of the ATLAS Collaboration.
Reproduction of this article or parts of it is allowed as specified in the CC-BY-3.0 license.
25 October 2014
arXiv:1411.2355v1 [hep-ex] 10 Nov 2014
STUDY OF SINGLE TOP PRODUCTION
AT HIGH ENERGY ELECTRON
POSITRON COLLIDERS
I.Garc´ıa, M.Perell´o, E.Ros, M.Vos
IFIC (Univ. Valencia - CSIC)
Top production will play a important role in future high energy electron–positron colliders.
Detailed calculations are already available for the process e+ e− → tt, but single top events
have mostly been neglected so far. We evaluate the relevance of these events and advocate
the exploration of the related process e+ e− → W + bW −¯b.
1
Introduction
A high-luminosity, high-energy, linear e+ e− collider yields excellent opportunities for precision tests of the Standard Model of particle physics. The combination of precisely calculable
electroweak production and strict control of the initial state with the relatively benign experimental environment and state-of-the-art detector systems allow for a characterization of
Standard Model and new physics processes with a precision that goes well beyond what can
be achieved at hadron colliders.
Two projects of linear electron-positron colliders are being considered: the International
Linear Collider (ILC [1, 2]) and the Compact Linear Collider (CLIC [3]). The physics case for
a linear e+ e− machine has been made in great detail in References [4–11]. The specific case of
a multi-TeV e+ e− collider is discussed in References [12–14]. In both cases, the center-of-mass
√
energy will exceed s= 350 GeV, the threshold for top quark pair production. Unlike other
quarks, the top quark has never been produced in e+ e− machines, and therefore a precise
measurement of electroweak top quark pair production is missing. The study of top quark
properties is therefore one of the most exciting prospects for a future linear collider [15].
Detailed full-simulation studies have been made of the prospects for a precise top quark mass
measurement [16] and characterization of the tt¯Z and tt¯γ vertices [17].
Single top production, through the e+ e− → W − t¯b, W + t¯b process depicted in the central
√
panel of Figure 1, is abundant at e+ e− colliders that operate at s >300 GeV. Note that
for the t → bW decay, this process gives rise to the same W + bW −¯b final state as top pair
production. The same is true for a third group of processes: W W Z, W W h and W W γ
1
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–5
D0 -D¯ 0 mixing and CP violation results from Belle
N.K. Nisar
arXiv:1411.2083v1 [hep-ex] 8 Nov 2014
Tata Institute of Fundamental Research
Homi Bhabha Road, Colaba, Mumbai 400005, INDIA
Abstract
We report the results on D0 -D¯ 0 mixing in the decays of D0 → K + π− and D0 → KS0 π+ π− , and CP violation in
D → π0 π0 using a data sample with an integrated luminosity of about 1 ab−1 recorded with the Belle detector,
at different center of mass energies. The mixing is observed in D0 → K + π− with the mixing parameters x02 =
(0.09 ± 0.22) × 10−3 , y0 = (4.6 ± 3.4) × 10−3 and the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay
rates RD = (3.53 ± 0.13) × 10−3 , where the quoted uncertainties combine both statistical and systematic contributions.
For the D0 → KS0 π+ π− decay, assuming CP conservation we measure mixing parameters x = (0.56 ± 0.19+0.03+0.06
−0.09−0.09 )%
+0.04+0.03
and y = (0.30 ± 0.15−0.05−0.06
)%, where the uncertainties are statistical, experimental systematics, and that due to
amplitude model. We measure the mixing parameters allowing CP violation for this decay mode, and obtain |q/p| =
+3 ◦
0.90+0.16+0.05+0.06
−0.15−0.04−0.05 and arg(q/p)=(−6 ± 11 ± 3−4 ) that are consistent with no CP violation. The time-integrated CP
0
0 0
asymmetry in the decay D → π π is measured to be, [−0.03 ± 0.64(stat) ± 0.10(syst)]%, consistent with CP
conservation. We also present an updated measurement of CP asymmetry in D0 → KS0 π0 .
0
Keywords: meson-antimeson mixing, CP violation, charm sector, time-integrated CP asymmetry, decays of charm
mesons, charm studies from Belle
1. Introduction
In the mixing, a pure flavor state of D0 or D¯ 0 at its
production vertex (at time t=0) becomes a mixture of
both D0 and D¯ 0 in moments later. Time evolution of
the neutral D system is described by a non-hermitian
E
Hamiltonian, and its eigenstates DH,L = p D0 ±
E
q D¯ 0 , are known as mass eigenstates. As evident, the
mass eigenstates are a mixture of the flavor eigen states,
which causes mixing. This mixing can proceeds either
via a short-distance effect involving virtual quarks and
W boson, or through a long-distance contribution that
involves real kaons or pions in the intermediate state.
The phenomenology of mixing is described by two parameters, x = (mH −mL )/Γ and y = (ΓH −ΓL )/2Γ, where
mH , mL are masses and ΓH , ΓL are widths of the mass
eigenstates. These mixing parameters are well measured for B0 , B0s and K 0 mesons, but not for D0 mesons.
Complex parameters p and q appearing in the ex-
pression of mass eigenstates describe indirect CP violation, with |p/q| , 1 gives CP violation in mixing while
arg(p/q) , 0 leads to CP violation due to interference
between decays with and without mixing. On the other
hand, the direct CP violation arises from the difference
in amplitudes for particles and their antiparticles decaying to some final state. The phenomenon of CP violation
is well established in B0 and K 0 systems, while it is not
observed in the charm sector. The contribution of indirect CP violation is mode independent for any neutral
mesons, while the direct component is mode dependent.
Only time integrated CP asymmetry, a sum of the indirect and direct asymmetries, can be measured for decays
in which final state is comprised neutral particles. In the
case of D0 decays, indirect CP violation is measured
to be consistent with zero [1]. So for decays such as
D0 → π0 π0 and D0 → KS0 π0 , one is effectively measuring the direct CP asymmetry. Within the standard model
Belle Preprint 2014-16
KEK Preprint 2014-27
arXiv:1411.2035v1 [hep-ex] 7 Nov 2014
BELLE
Measurement of B 0 → Ds− KS0 π + and B + → Ds− K + K + branching
fractions
J. Wiechczynski,45 J. Stypula,45 A. Abdesselam,56 I. Adachi,15, 11 K. Adamczyk,45
H. Aihara,61 S. Al Said,56, 28 K. Arinstein,4 D. M. Asner,48 V. Aulchenko,4 T. Aushev,23
R. Ayad,56 A. M. Bakich,55 V. Bansal,48 V. Bhardwaj,42 B. Bhuyan,17 A. Bobrov,4
5
ˇ
A. Bondar,4 G. Bonvicini,66 A. Bozek,45 M. Braˇcko,35, 24 T. E. Browder,14 D. Cervenkov,
V. Chekelian,36 B. G. Cheon,13 K. Cho,29 V. Chobanova,36 S.-K. Choi,12 Y. Choi,54
66
36, 58
23, 38
3
5
5
D. Cinabro, J. Dalseno,
M. Danilov,
J. Dingfelder, Z. Doleˇzal, Z. Dr´asal,
A. Drutskoy,23, 38 S. Eidelman,4 H. Farhat,66 J. E. Fast,48 T. Ferber,8 O. Frost,8 V. Gaur,57
4
66
4
N. Gabyshev, S. Ganguly, A. Garmash, D. Getzkow,9 R. Gillard,66 Y. M. Goh,13
O. Grzymkowska,45 J. Haba,15, 11 T. Hara,15, 11 K. Hayasaka,41 H. Hayashii,42 X. H. He,49
W.-S. Hou,44 M. Huschle,26 H. J. Hyun,31 T. Iijima,41, 40 A. Ishikawa,60 R. Itoh,15, 11
Y. Iwasaki,15 I. Jaegle,14 D. Joffe,27 K. K. Joo,6 T. Julius,37 K. H. Kang,31 E. Kato,60
T. Kawasaki,46 H. Kichimi,15 D. Y. Kim,53 J. B. Kim,30 J. H. Kim,29 M. J. Kim,31
S. H. Kim,13 Y. J. Kim,29 K. Kinoshita,7 B. R. Ko,30 P. Kodyˇs,5 P. Kriˇzan,33, 24
P. Krokovny,4 T. Kuhr,26 T. Kumita,63 A. Kuzmin,4 Y.-J. Kwon,68 J. S. Lange,9
I. S. Lee,13 Y. Li,65 L. Li Gioi,36 J. Libby,18 D. Liventsev,15 P. Lukin,4 D. Matvienko,4
K. Miyabayashi,42 H. Miyata,46 R. Mizuk,23, 38 G. B. Mohanty,57 A. Moll,36, 58 T. Mori,40
R. Mussa,22 M. Nakao,15, 11 T. Nanut,24 Z. Natkaniec,45 N. K. Nisar,57 S. Nishida,15, 11
S. Ogawa,59 S. Okuno,25 P. Pakhlov,23, 38 G. Pakhlova,23 C. W. Park,54 H. Park,31
T. K. Pedlar,34 M. Petriˇc,24 L. E. Piilonen,65 E. Ribeˇzl,24 M. Ritter,36 A. Rostomyan,8
Y. Sakai,15, 11 S. Sandilya,57 L. Santelj,24 T. Sanuki,60 Y. Sato,60 V. Savinov,50
O. Schneider,32 G. Schnell,1, 16 C. Schwanda,21 K. Senyo,67 O. Seon,40 M. E. Sevior,37
V. Shebalin,4 C. P. Shen,2 T.-A. Shibata,62 J.-G. Shiu,44 B. Shwartz,4 A. Sibidanov,55
F. Simon,36, 58 Y.-S. Sohn,68 E. Solovieva,23 M. Stariˇc,24 M. Steder,8 M. Sumihama,10
U. Tamponi,22, 64 K. Tanida,52 G. Tatishvili,48 Y. Teramoto,47 F. Thorne,21
K. Trabelsi,15, 11 M. Uchida,62 T. Uglov,23, 39 Y. Unno,13 S. Uno,15, 11 P. Urquijo,3
Y. Usov,4 C. Van Hulse,1 P. Vanhoefer,36 G. Varner,14 A. Vinokurova,4 V. Vorobyev,4
A. Vossen,19 M. N. Wagner,9 C. H. Wang,43 M.-Z. Wang,44 P. Wang,20 M. Watanabe,46
Y. Watanabe,25 K. M. Williams,65 E. Won,30 J. Yamaoka,48 S. Yashchenko,8
Y. Yook,68 Y. Yusa,46 Z. P. Zhang,51 V. Zhilich,4 V. Zhulanov,4 and A. Zupanc24
(The Belle Collaboration)
1
University of the Basque Country UPV/EHU, 48080 Bilbao
2
Beihang University, Beijing 100191
3
University of Bonn, 53115 Bonn
Typeset by REVTEX
1
46
Niigata University, Niigata 950-2181
Osaka City University, Osaka 558-8585
Pacific Northwest National Laboratory, Richland, Washington 99352
49
Peking University, Beijing 100871
50
University of Pittsburgh, Pittsburgh, Pennsylvania 15260
51
University of Science and Technology of China, Hefei 230026
52
Seoul National University, Seoul 151-742
53
Soongsil University, Seoul 156-743
54
Sungkyunkwan University, Suwon 440-746
55
School of Physics, University of Sydney, NSW 2006
56
Department of Physics, Faculty of Science, University of Tabuk, Tabuk 71451
57
Tata Institute of Fundamental Research, Mumbai 400005
58
Excellence Cluster Universe, Technische Universit¨at M¨
unchen, 85748 Garching
59
Toho University, Funabashi 274-8510
60
Tohoku University, Sendai 980-8578
61
Department of Physics, University of Tokyo, Tokyo 113-0033
62
Tokyo Institute of Technology, Tokyo 152-8550
63
Tokyo Metropolitan University, Tokyo 192-0397
64
University of Torino, 10124 Torino
65
CNP, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
66
Wayne State University, Detroit, Michigan 48202
67
Yamagata University, Yamagata 990-8560
68
Yonsei University, Seoul 120-749
47
48
Abstract
We report a measurement of the B 0 and B + meson decays to the Ds− KS0 π + and Ds− K + K +
final states, respectively, using 657 × 106 BB pairs collected at the Υ(4S) resonance with the Belle
detector at the KEKB asymmetric-energy e+ e− collider. Using the Ds− → φπ − , K ∗ (892)0 K −
and KS0 K − decay modes for the Ds reconstruction, we measure the following branching fractions:
B(B 0 → Ds− KS0 π + ) = [0.47 ± 0.06(stat) ± 0.05(syst)] × 10−4 and B(B + → Ds− K + K + ) = [0.93 ±
0.22(stat) ± 0.10(syst)] × 10−5 . We find the ratio of the branching fraction of B + → Ds− K + K + to
that of the analogous Cabibbo favored B + → Ds− K + π + decay to be RB = 0.054 ± 0.013(stat) ±
0.006(syst), which is consistent with the na¨ıve factorization model. We also observe a deviation
from the three-body phase-space model for both studied decays.
PACS numbers: 13.20.He, 14.40.Nd, 14.40.Lb
3
Viscous Effects on the Mapping of the Initial to Final State in Heavy Ion Collisions
Fernando G. Gardim,1 Jacquelyn Noronha-Hostler,2, 3 Matthew Luzum,4, 5, 6 and Fr´ed´erique Grassi3
1
arXiv:1411.2574v1 [nucl-th] 10 Nov 2014
Instituto de Ciˆencia e Tecnologia, Universidade Federal de Alfenas,
Cidade Universit´
aria, 37715-400 Po¸cos de Caldas, MG, Brazil
2
Department of Physics, Columbia University, New York, 10027, USA
3
Instituto de F´ısica, Universidade de S˜
ao Paulo, C.P. 66318, 05315-970 S˜
ao Paulo, SP, Brazil
4
McGill University, 3600 University Street, Montreal QC H3A 2TS, Canada
5
Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
6
Departamento de F´ısica de Part´ıculas and IGFAE,
Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Galicia-Spain
We investigate the correlation between various aspects of the initial geometry of heavy ion collisions at the Relativistic Heavy Ion Collider energies and the final anisotropic flow, using v-USPhydro,
a 2+1 event-by-event viscous relativistic hydrodynamical model. We test the extent of which shear
and bulk viscosity affect the prediction of the final flow harmonics, vn , from the initial eccentricities,
εn . We investigate in detail the flow harmonics v1 through v5 where we find that v1 , v4 , and v5
are dependent on more complicated aspects of the initial geometry that are especially important
for the description of peripheral collisions, including a non-linear dependence on eccentricities as
well as a dependence on shorter-scale features of the initial density. Furthermore, we compare our
results to previous results from NeXSPheRIO, a 3+1 relativistic ideal hydrodynamical model that
has a non-zero initial flow contribution, and find that the combined contribution from 3+1 dynamics
and non-zero, fluctuating initial flow decreases the predictive ability of the initial eccentricities, in
particular for very peripheral collisions, but also disproportionately in central collisions.
I.
INTRODUCTION
Ultrarelativistic heavy ion collisions are essential in
probing strongly interacting matter at high energy
regimes. Relativistic hydrodynamics has been able to
accurately describe a large amount of experimental data
from these collisions [1]. Predictions from ideal hydrodynamics describe quite well some observables, such as
elliptic flow and higher flow harmonics [2–6], and dihadron correlations [7], which suggest that the Quark
Gluon Plasma is a nearly perfect fluid. However, predictions are the most successful in the more central collisions (as compared to peripheral ones) where the matter
is the most dense and shear viscosity plays the smallest
role. Furthermore, it has been recently shown that [8, 9]
bulk viscosity can compensate the effect of shear viscosity and can improve the fit to experimental data [10], so
it is important to include both viscous effects. Thus, to
improve the predictions and take into account dissipative
effects, which are more important in smaller systems [11],
viscous hydrodynamics is used in this paper within the
event-by-event code, v-USPhydro [8, 9]. However, only
small shear and bulk viscosities are considered due to the
previous success of ideal hydrodynamics.
The study of strongly-coupled matter with hydrodynamics requires that one supply a set of initial conditions, then evolve them through ideal [12–16] or viscous [6, 8, 9, 17–19] hydrodynamics, and at the end, compute the particle emission. The particle distribution of
each individual event reflects characteristics of the initial conditions, such as the energy density profile and
the initial flow. In a non-central collision the averaged
initial density profile presents an almond shape, which
is commonly characterized by an elliptic eccentricity ε2 .
Hydrodynamic evolution then converts this spatial asymmetry into an asymmetry in the final particle distribution, given by the elliptic flow v2 . Di-hadron azimuthal
correlations data cannot be theoretically understood as
coming from smooth density profiles, but rather in eventby-event hydrodynamics with fluctuations in the initial
conditions [12]. These fluctuations generate non-zero odd
Fourier harmonics at mid-rapidity, for example a triangular anisotropy v3 in the azimuthal particle distribution,
as a consequence of an average triangular anisotropy in
the initial density condition [20].
To construct more realistic models for early-time collision dynamics, and provide a more direct link between
experimental data and the properties of initial conditions it is necessary to understand the anisotropic flow
response to the initial state properties. Much effort has
been made in that direction [5, 6, 16, 19–24] – where
primarily only ideal hydrodynamics and no initial flow
was used – demonstrating that elliptic flow comes mainly
from the elliptic shape and triangular flow comes from the
initial triangularity ε3 , but quadrangular and pentagonal
flow do not come only from quadrangularity and pentagularity [23, 25], but also from combinations of ε2 and ε3 ,
given by the cumulant expansion of the initial density
profile [25]. Directed flow v1 seems to come from dipole
asymmetry ε1 [26], but it has not been well studied.
The goal of this work is to improve our understanding
of the detailed relationship between the initial conditions
and the final-measured observables. We do this by solving event-by-event ideal and viscous hydrodynamics for
Monte Carlo Glauber initial conditions, using both shear
and bulk viscosity, as well as comparing the results to
realistic initial conditions for ideal hydrodynamics, NeXSPheRIO. Using this information, we quantitatively in-
Phase Diagram of Wilson and Twisted Mass
Fermions at finite isospin chemical potential
arXiv:1411.2570v1 [hep-lat] 10 Nov 2014
M. Kieburg∗
Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
E-mail: mkieburg@physik.uni-bielefeld.de
K. Splittorff
Discovery Center, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17,
DK-2100, Copenhagen Ø, Denmark
E-mail: split@nbi.dk
J. J. M. Verbaarschot
Department of Physics and Astronomy, State University of New York at Stony Brook, NY
11794-3800, USA
E-mail: jv@chi.physics.sunysb.edu
S. Zafeiropoulos
Laboratoire de Physique Corpusculaire, Université Blaise Pascal, CNRS/IN2P3 63177 Aubière
Cedex, France
Institut für Theoretische Physik, Goethe-Universität Frankfurt,
Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
E-mail: zafeiro@th.physik.uni-frankfurt.de
Wilson Fermions with untwisted and twisted mass are widely used in lattice simulations. Therefore one important question is whether the twist angle and the lattice spacing affect the phase
diagram. We briefly report on the study of the phase diagram of QCD in the parameter space of
the degenerate quark masses, isospin chemical potential, lattice spacing, and twist angle by employing chiral perturbation theory. Moreover we calculate the pion masses and their dependence
on these four parameters.
The 32nd International Symposium on Lattice Field Theory
23-28 June, 2014
Columbia University New York, NY
∗ Speaker.
c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
http://pos.sissa.it/
UMN-TH-3409/14
arXiv:1411.2521v1 [astro-ph.CO] 10 Nov 2014
Prepared for submission to JCAP
Parity-violating and anisotropic
correlations in pseudoscalar inflation
Nicola Bartolo,a,b Sabino Matarrese,a,b Marco Pelosoc and
Maresuke Shiraishia,b
a Dipartimento
di Fisica e Astronomia “G. Galilei”,
Universit`
a degli Studi di Padova, via Marzolo 8, I-35131, Padova, Italy
b INFN, Sezione di Padova,
via Marzolo 8, I-35131, Padova, Italy
c School of Physics and Astronomy,
University of Minnesota, Minneapolis 55455, USA
Abstract. A pseudo-scalar inflaton field can have interesting phenomenological signatures
associated with parity violation. The existing analyses of these signatures typically assume
statistical isotropy. In the present work we instead investigate the possibility that a pseudoscalar inflaton is coupled to a vector field carrying a small but non-negligible vacuum expectation value (vev) coherent over our Hubble patch. We show that, in such case, correlators
involving the primordial curvature perturbations and gravitational waves violate both statistical isotropy and parity symmetry. We compute the Cosmic Microwave Background (CMB)
temperature anisotropies (T) and polarization (E/B) generated by these primordial modes.
The CMB two-point correlation functions present distinct signals of broken rotational and
parity invariance. Specifically, we find non-vanishing TT, TE, EE and BB correlators between ℓ1 and ℓ2 = ℓ1 ± 1 multipoles, and non-vanishing TB and EB correlators between ℓ1
and ℓ2 = ℓ1 ±2 multipoles. Such signatures are specific of the models under consideration and
they cannot be generated if one of parity and isotropy is preserved. As a specific example we
consider the simple case in which the vector field has just an “electric” background component decaying in the standard way as a−2 . In this case a strong scale-dependent quadrupolar
modulation of the primordial power spectra is generated and we find that almost noiseless
data of the large-scale temperature and E-mode polarization anisotropies (like, e.g., the ones
provided by WMAP or Planck) should be able to constrain the quadrupolar amplitude coefficients g2M of the primordial scalar power spectrum (normalized at the pivot scale comparable
to the present horizon size k0−1 = 14 Gpc) down to g2M = 30 (68%CL).
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–3
Induced magnetic moment in the magnetic catalysis of chiral symmetry breaking
Efrain J. Ferrer and Vivian de la Incera
arXiv:1411.2493v1 [nucl-th] 10 Nov 2014
Department of Physics, The University of Texas at El Paso 500 W. University Ave., EL Paso, TX 79968
Abstract
The chiral symmetry breaking in a Nambu-Jona-Lasinio effective model of quarks in the presence of a magnetic
field is investigated. We show that new interaction tensor channels open up via Fierz identities due to the explicit
breaking of the rotational symmetry by the magnetic field. We demonstrate that the magnetic catalysis of chiral
symmetry breaking leads to the generation of two independent condensates, the conventional chiral condensate and a
spin-one condensate. While the chiral condensate generates, as usual, a dynamical fermion mass, the new condensate
enters as a dynamical anomalous magnetic moment in the dispersion of the quasiparticles. Since the pair, formed by
a quark and an antiquark with opposite spins, possesses a resultant magnetic moment, an external magnetic field can
align it giving rise to a net magnetic moment for the ground state. The two condensates contribute to the effective
mass of the LLL quasiparticles in such a way that the critical temperature for chiral symmetry restoration becomes
enhanced.
Keywords: Magnetic catalysis of chiral symmetry breaking in NJL model.
1. Introduction
The phases of matter under strong magnetic fields
constitute an active topic of interest in light of the experimental production of large magnetic fields in heavy-ion
collisions, and also because of the existence of strongly
magnetized astrophysical compact objects. On the other
hand, from a theoretical point of view there exist contradictory results about the influence of a magnetic field
on the chiral and deconfinement transitions of QCD [1].
Of particular interest for the present paper are some
recently obtained results [2] on the influence of a magnetic field on the condensate structures characterizing
the QCD chiral transition. A magnetic field is known
to produce the catalysis of chiral symmetry breaking
(MCχSB) [3] in any system of fermions with arbitrarily
weak attractive interaction. This effect has been actively
investigated for the last two decades [4]. In the original
studies of the MCχSB, the catalyzed chiral condensate
was assumed to generate only a dynamical mass for the
fermion. Recently, however, it has been shown that in
QED [5] the MCχSB leads to a dynamical fermion mass
and inevitably also to a dynamical anomalous magnetic
moment (AMM). This is connected to the fact that the
AMM does not break any symmetry that has not already been broken by the other condensate. The dynamical AMM in massless QED leads, in turn, to a nonperturbative Lande g-factor and Bohr magneton proportional to the inverse of the dynamical mass. The induction of the AMM also gives rise to a non-perturbative
Zeeman effect [5]. An important aspect of the MCχSB
is its universal character for theories of charged massless fermions in a magnetic field. Therefore, it is naturally to expect that the dynamical generation of the
AMM shall permeate all the models of interacting massless fermions in a magnetic field.
As follows, we consider the dynamical generation
of a net magnetic moment in the ground state of a
one-flavor Nambu-Jona-Lasinio (NJL) model in a magnetic field and discuss its implications for the chiral
phase transition at finite temperature. The AMM of the
quark/antiquark in the pair points in the same direction,
as the pair is formed by particles with opposite spins
and opposite charges. Hence, the pair has a nonzero
arXiv:1411.2453v1 [hep-lat] 10 Nov 2014
Lattice investigation of heavy meson interactions
Bj¨
orn Wagenbach1 , Pedro Bicudo2 , Marc Wagner1,3
1
2
3
Goethe-Universit¨
at Frankfurt am Main, Institut f¨
ur Theoretische Physik,
Max-von-Laue-Straße 1, D-60438 Frankfurt am Main, Germany
Dep. F´ısica and CFTP, Instituto Superior T´ecnico, Av. Rovisco Pais, 1049-001 Lisboa,
Portugal
European Twisted Mass Collaboration (ETMC)
E-mail: wagenbach@th.physik.uni-frankfurt.de
Abstract. We report on a lattice investigation of heavy meson interactions and of tetraquark
candidates with two very heavy quarks. These two quarks are treated in the static limit, while
the other two are up, down, strange or charm quarks of finite mass. Various isospin, spin and
parity quantum numbers are considered.
1. Introduction
We study the potential of two static quarks in the presence of two quarks of finite mass. While in
¯ Qll),
¯
[1, 2, 3] we have exclusively considered two static antiquarks and two light quarks (Q
where
¯
¯
¯
¯
l ∈ {u, d}, here we also use s and c quarks, i.e. investigate QQss and QQcc, to obtain certain
insights regarding the quark mass dependence of the static antiquark-antiquark interaction. We
¯ ¯ll, QQ¯
¯ ss and QQ¯
¯ cc.
also discuss first steps regarding the static quark-antiquark case, i.e. QQ
¯
¯
¯
QQqq systems as well as QQ¯
q q systems have been studied also by other groups (cf. e.g.
[4, 5, 6, 7, 8, 9, 10, 11, 12]).
2. Creation operators and trial states
¯ Qqq
¯ and QQ¯
¯ qq potentials V (r) are extracted from correlation functions
The Q
C(t) ≡ hΩ|O† (t)O(0)|Ωi
(1)
according to
V (r) =large t Veff (r, t)
,
Veff (r, t) ≡
1
ln
a
C(t)
,
C(t + a)
(2)
where a is the lattice spacing and O denote suitable creation operators, which are discussed in
detail below. For an introduction to lattice hadron spectroscopy cf. e.g. [13].
¯ mesons”)
2.1. Static-light mesons (“B and B
The starting point are static-light mesons, which either consist of a static quark Q and an
¯ and a quark q with q ∈ {u, d, s, c}. These mesons can
antiquark q¯ or of a static antiquark Q
be labeled by parity P = ±, by the z-component of the light quark spin jz = ±1/2 (j = 1/2,
because we do not consider gluonic excitations) and in case of q ∈ {u, d} by the z-component
Relativistic third-order viscous corrections to the entropy four-current from kinetic
theory
Chandrodoy Chattopadhyay1 , Amaresh Jaiswal2 , Subrata Pal1 , and Radoslaw Ryblewski3
1
arXiv:1411.2363v1 [nucl-th] 10 Nov 2014
Department of Nuclear and Atomic Physics, Tata Institute of
Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
2
GSI, Helmholtzzentrum f¨
ur Schwerionenforschung,
Planckstrasse 1, D-64291 Darmstadt, Germany and
3
The H. Niewodnicza´
nski Institute of Nuclear Physics,
Polish Academy of Sciences, PL-31342 Krak´
ow, Poland
(Dated: November 11, 2014)
By employing a Chapman-Enskog like iterative solution of the Boltzmann equation in relaxationtime approximation, we derive a new expression for the entropy four-current up to third order in
gradient expansion. We show that unlike second-order and third-order entropy four-current obtained
using Grad’s method, there is a non-vanishing entropy flux in the present third-order expression.
We further quantify the effect of the higher-order entropy density in the case of boost-invariant onedimensional longitudinal expansion of a system. We demonstrate that the results obtained using
third-order evolution equation for shear stress tensor, derived by employing the method of ChapmanEnskog expansion, show better agreement with the exact solution of the Boltzmann equation as well
as with the parton cascade BAMPS, as compared to those obtained using the third-order equations
from the method of Grad’s 14-moment approximation.
PACS numbers: 05.20.Dd, 47.75+f, 47.10.-g, 47.10.A-
I.
INTRODUCTION
Study of the space-time evolution and non-equilibrium
properties of hot and dense matter produced in highenergy heavy-ion collisions, within the framework of relativistic viscous hydrodynamics, has gained widespread
interest; see Ref. [1] for a recent review. Hydrodynamics
is an effective theory that describes the long-wavelength
limit of the microscopic dynamics of a system. As a
macroscopic theory which describes the space-time evolution of the energy-momentum tensor, it is much less involved than microscopic descriptions such as kinetic theory. In order to study the hydrodynamic evolution of a
system, it is natural to first employ the equations of ideal
hydrodynamics. However, ideal hydrodynamics is based
on the unrealistic assumption of local thermodynamic
equilibrium which results in isentropic evolution. Moreover, since the quantum mechanical uncertainty principle
provides a lower bound on the shear viscosity to entropy
density ratio [2, 3], the dissipative effects can not be ignored.
Eckart [4] and Landau and Lifshitz [5] were the first
to formulate a relativistic theory of dissipative hydrodynamics, each with a different choice for the definition of hydrodynamic four-velocity. These theories are
based on the assumption that the entropy four-current
is linear in dissipative quantities and hence they are also
known as first-order theories of dissipative fluids. The
resulting equations for the dissipative quantities are essentially the relativistic analogue of the Navier-Stokes
equations. However, the resulting equations of motion
lead to parabolic differential equations which suffer from
acausality and numerical instability. In order to rectify
the undesirable features of first-order theories, extended
theories of dissipative fluids were introduced by Grad [6],
M¨
uller [7] and Israel and Stewart [8]. These theories are
based on the assumption that the entropy four-current
contains terms quadratic in the dissipative fluxes and
therefore are also known as second-order theories. The
resulting equations of motion are hyperbolic in nature
which preserves causality [9] but may not guarantee stability.
Second-order Israel-Stewart (IS) hydrodynamics has
been quite successful in explaining a wide range of collective phenomena observed in ultra-relativistic heavyion collisions [1]. Despite its successes, the formulation
of IS theory is based on certain approximations and assumptions. For instance, the original IS theory employs
an arbitrary choice of the second moment of the Boltzmann equation to obtain the equations of motion for the
dissipative currents [8]. Another assumption inherent in
IS theory is the use of Grad’s 14-moment approximation for the non-equilibrium distribution function [6, 8].
Moreover, the IS theory is a second-order theory which
neglects contributions from higher-order terms in the entropy four-current. It is thus of interest to extend the
second-order theory beyond its present scope and determine the associated transport coefficients for a hydrodynamic system.
In a non-equilibrium system, the presence of thermodynamic gradients results in thermodynamic forces which
in turn gives rise to various transport phenomena. Therefore transport coefficients such as viscosity, diffusivity
and conductivity, are important to characterize the dynamics of a system. Precise knowledge of these transport coefficients and associated length and time scales
is necessary in comparing observables with theoretical
predictions. In order to calculate these transport coef-
Models of the Primordial Standard Clock
arXiv:1411.2349v1 [astro-ph.CO] 10 Nov 2014
Xingang Chen1 , Mohammad Hossein Namjoo1 and Yi Wang2
1
Department of Physics, The University of Texas at Dallas, Richardson, TX 75083, USA
2
Center for Theoretical Cosmology,
Department of Applied Mathematics and Theoretical Physics,
University of Cambridge, Cambridge CB3 0WA, UK
Abstract
Oscillating massive fields in the primordial universe can be used as Standard Clocks. The
ticks of these oscillations induce features in the density perturbations, which directly record
the time evolution of the scale factor of the primordial universe, thus if detected, provide
a direct evidence for the inflation scenario or the alternatives. In this paper, we construct
a full inflationary model of primordial Standard Clock and study its predictions on the
density perturbations. This model provides a full realization of several key features proposed
previously. We compare the theoretical predictions from inflation and alternative scenarios
with the Planck 2013 temperature data on Cosmic Microwave Background (CMB), and
identify a statistically marginal but interesting candidate. We discuss how future CMB
temperature and polarization data, non-Gaussianity analysis and Large Scale Structure data
may be used to further test or constrain the Standard Clock signals.
arXiv:1411.2294v1 [hep-th] 9 Nov 2014
DESY 14-171
Analytic structure of the n = 7 scattering amplitude in
N = 4 SYM theory in multi-Regge kinematics:
Conformal Regge cut contribution
Jochen Bartels,a Andrey Kormilitzin,a,b Lev N.Lipatov1a,c,d
a
II. Institut f¨
ur Theoretische Physik, Universit¨
at Hamburg, Luruper Chaussee 149,
D-22761 Hamburg, Germany
b
Oxford-Man Institute, University of Oxford, Eagle House, Walton Well Road, Oxford, OX2 6ED,
United Kingdom
c
Physics Department, St.Petersburg State University, Ulyanovskaya 3, St.Petersburg 198504,Russia
c
Theoretical Physics Department, Petersburg Nuclear Physics Institute, Orlova Roscha, Gatchina,
188300, St. Petersburg, Russia
E-mail: jochen.bartels@desy.de, andrey.kormilitzin@desy.de,
lipatov@mail.desy.de
Abstract: In this second part of our investigation [1] of the analytic structure of the
2 → 5 scattering amplitude in the planar limit of N = 4 SYM in multi-Regge kinematics
we compute, in all kinematic regions, the Regge cut contributions in leading order. The
results are infrared finite and conformally invariant.
1
This work has been supported by the grant RFBR 13-02-01246a
arXiv:1411.2280v1 [astro-ph.CO] 9 Nov 2014
EPJ Web of Conferences will be set by the publisher
DOI: will be set by the publisher
c Owned by the authors, published by EDP Sciences, 2014
Antimatter in the universe and laboratory
A.D. Dolgov1,2,3, a
1
University of Ferrara, Ferrara 40100, Italy
NSU, Novosibirsk, 630090, Russia
3
ITEP, Moscow, 117218, Russia
2
Abstract. Possible signatures which may indicate an existence of antimatter in the
Galaxy and in the early universe are reviewed. A model which could give rise to abundant
antimatter in the Galaxy is considered.
1 Introduction
86 years ago a fantastic breakthrough in particle physics was done by Paul Dirac [1] who “with the tip
of his pen” predicted a whole world of antimatter (not just a small planet). He assumed initially that
positively charged "electron" was proton. At that time physicists were rather reluctant to introduce
new particles, a drastic contrast to the present days. However, the critics by Oppenheimer that in this
case hydrogen would be very unstable, if proton was a hole in the negative continuum, forced Dirac in
1931 to conclude that "anti-electron" is a new particle, positron, with the same mass as e− . Very soon
after that, in 1933, Carl Anderson, discovered positron. Dirac received his Nobel prize immediately
after this discovery, and Anderson got it three years alter, in 1936. According to the Anderson words:
the discovery was not was not difficult, simply nobody looked for that.
In his Nobel lecture “Theory of electrons and positrons”, in December 12, 1933 Dirac said: “It is
quite possible that...these stars being built up mainly of positrons and negative protons. In fact, there
may be half the stars of each kind. The two kinds of stars would both show exactly the same spectra,
and there would be no way of distinguishing them by present astronomical methods.” However, we
see in what follows that there are such ways and we can conclude weather a star is made of antimatter
making astronomical observations from the Earth.
It is interesting that in 1898, 30 years before Dirac and one year after discovery of electron (J.J.
Thomson, 1897), Arthur Schuster (another British physicist) conjectured that there might be other
sign electricity, which he called antimatter and supposed that there might be entire solar systems,
made of antimatter and indistinguishable from ours [2]. Schuster made wild guess that matter and
antimatter are capable to annihilate and produce energy. It happened to be ingenious and true. He
also believed that matter and antimatter were gravitationally repulsive, since antimatter particles had
negative mass. Two such objects on close contact would have vanishing mass!. As we know now, this
is not the case and matter and antimatter have attractive gravity.
Now we encounter at a new level these, more than century old, questions:
Whether antiworlds, antistars or similar astronomically large pieces of antimatter exist in the universe?
a e-mail: dolgov@fe.infn.it
Prepared for submission to JHEP
arXiv:1411.2211v1 [hep-lat] 9 Nov 2014
Two dimensional gluon propagators in maximally
Abelian gauge in SU(2) Lattice QCD
Shinya Gongyoa,b
a
Department of Physics, New York University, 4 Washington Place, New York, New York 10003,
USA
b
Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake,
Sakyo, Kyoto 606-8502, Japan
E-mail: gongyo@ruby.scphys.kyoto-u.ac.jp
Abstract: Using SU(2) lattice QCD in two dimensions, we study diagonal and offdiagonal gluon propagators in the maximally Abelian gauge (MAG) with U(1)3 Landau
gauge fixing. These propagators are investigated both in momentum space and coordinate
space. The Monte Carlo simulation is performed at β = 7.99, 30.5, and 120 on 622 , 1282 ,
and 2562 at the quenched level. In the momentum space, the transverse component of
the diagonal gluon propagator shows suppression with increasing β in the infrared region
and the dressing function at β = 120 has a maximum at p2 ≃ 4GeV, while the transverse
component of the off-diagonal gluon propagator does not show the β-dependence and the
dressing function does not have a maximum. This behavior indicates that the effect of
the Gribov copies is found for the diagonal gluon, consistent with the result obtained by
the Gribov-Zwanziger action in the MAG. In addition, this behavior supports that the
Abelian dominance is not found in two dimensions. In the coordinate space, the diagonal
gluon propagator decreases as β increases at long distance. In particular, at β = 120 the
diagonal propagator decreases more rapidly with increasing distance than the off-diagonal
propagator. These behaviors also indicate the presence of Gribov copies and no Abelian
dominance in two dimensions. Furthermore, we also study these propagators at zerospatial-momentum. The result suggests that all of the spectral functions of diagonal and
off-diagonal gluons would have negative regions and thus they show the violation of the
Kallen-Lehmann representation.
Nucleon tensor charges and electric dipole moments
Mario Pitschmann,1 Chien-Yeah Seng,2 Craig D. Roberts,3 and Sebastian M. Schmidt4
1
arXiv:1411.2052v1 [nucl-th] 7 Nov 2014
Atominstitut, Technische Universit¨
at Wien, Stadionallee 2, A-1020 Wien, Austria
2
Amherst Center for Fundamental Interactions, Department of Physics,
University of Massachusetts Amherst, Amherst, MA 01003, USA
3
Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
4
Institute for Advanced Simulation, Forschungszentrum J¨
ulich and JARA, D-52425 J¨
ulich, Germany
(Dated: 7 November 2014)
A symmetry-preserving Dyson-Schwinger equation treatment of a vector-vector contact interaction is used to compute dressed-quark-core contributions to the nucleon σ-term and tensor charges.
The latter enable one to directly determine the effect of dressed-quark electric dipole moments
(EDMs) on neutron and proton EDMs. The presence of strong scalar and axial-vector diquark
correlations within ground-state baryons is a prediction of this approach. These correlations
are active participants in all scattering events and thereby enhance the contribution of the
singly-represented valence-quark relative to that of the doubly-represented quark for each quantity
considered herein. Regarding the proton σ-term and that part of the proton mass which owes to
explicit chiral symmetry breaking, with a realistic d-u mass splitting the singly-represented d-quark
contributes 40% more than the doubly-represented u-quark; and in connection with the proton’s
tensor charges, δT u, δT d, the ratio δT d/δT u is 8% larger than anticipated from simple quark
models. Of particular note, the size of δT u is a sensitive measure of the strength of dynamical
chiral symmetry breaking; and δT d measures the amount of axial-vector diquark correlation within
the proton, vanishing if such correlations are absent.
PACS numbers: 12.38.Lg, 14.20.Dh, 13.88.+e, 11.30.Er
I.
INTRODUCTION
In recent years a global approach to the description
of nucleon structure has emerged, one in which we may
express our knowledge of the nucleon in the Wigner distributions of its basic constituents and thereby provide
a multidimensional generalisation of the familiar parton
distribution functions (PDFs). The Wigner distribution
is a quantum mechanics concept analogous to the classical notion of a phase space distribution. Following
from such distributions, a natural interpretation of measured observables is provided by construction of quantities known as generalised parton distributions (GPDs)
[1–8] and transverse momentum-dependent distributions
(TMDs) [9–15]: GPDs are linked to a spatial tomography of the nucleon; and TMDs allow for its momentum
tomography. A new generation of experiments aims to
provide the empirical information necessary to develop a
phenomenology of nucleon Wigner distributions.
At leading-twist there are eight distinct TMDs, only
three of which are nonzero in the collinear limit; i.e., in
the absence of parton transverse momentum within the
target, k⊥ = 0: the unpolarized (f1 ), helicity (g1L ) and
transversity (h1T ) distributions. In connection with the
last of these, one may define the proton’s tensor charges
(q = u, d, . . .)
δT q =
Z
1
−1
dx hq1T (x) =
Z
0
1
¯
dx hq1T (x) − hq1T
(x) , (1)
which, as illustrated in Fig. 1, measures the light-front
number-density of quarks with transverse polarisation
parallel to that of the proton minus that of quarks
Preprint no. ACFI-T14-23
with antiparallel polarisation; viz., it measures any bias
in quark transverse polarisation induced by a polarisation of the parent proton. The charges δT q represent a
close analogue of the nucleon’s flavour-separated axialcharges, which measure the difference between the lightfront number-density of quarks with helicity parallel to
that of the proton and the density of quarks with helicity antiparallel [16]. In nonrelativistic systems the helicity and transversity distributions are identical because
boosts and rotations commute with the Hamiltonian.
The transversity distribution is measurable using
Drell-Yan processes in which at least one of the two colliding particles is transversely polarised [17]; but such
data is not yet available. Alternatively, the transversity
distribution is accessible via semi-inclusive deep-inelastic
scattering using transversely polarised targets and also in
unpolarised e+ e− processes, by studying azimuthal correlations between produced hadrons that appear in opnucleon spin
quark spin
−
Direction of motion
FIG. 1. The tensor charge, Eq. (1), measures the net lightfront distribution of transversely polarised quarks inside a
transversely polarized proton.
Renormalization-Group Evolution of Chiral Gauge Theories
Yan-Liang Shi (石炎亮) and Robert Shrock
arXiv:1411.2042v1 [hep-th] 7 Nov 2014
C. N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, N. Y. 11794
We calculate the ultraviolet to infrared evolution and analyze possible types of infrared behavior
for several asymptotically free chiral gauge theories with gauge group SU(N ) and massless chiral
fermions transforming according to a symmetric rank-2 tensor representation S and N + 4 copies
(flavors) of a conjugate fundamental representation F¯ , together with a vectorlike subsector with
chiral fermions in higher-dimensional representation(s). We construct and study three such chiral
gauge theories. These have respective vectorlike subsectors comprised of (a) p copies of fermions in
the adjoint representation, (b) N = 2k even and p copies of fermions in the antisymmetric rank-k
¯ fermions. Results are presented for beta functions,
tensor representation, and (c) p copies of {S + S}
their infrared zeros, and predictions from the most-attractive-channel approach for the formation of
bilinear fermion condensates. Importantly, we show that for these theories, the expected ultraviolet
to infrared evolution obeys a conjectured inequality concerning the field degrees of freedom for all
values of the parameters N and p characterizing each theory.
I.
INTRODUCTION
The question of how the properties of an asymptotically free chiral gauge theory change as a function of
the Euclidean momentum scale µ at which one measures
these properties is of fundamental physical interest. For
sufficiently large µ in the deep ultraviolet (UV), a theory of this type is weakly coupled and can be described
by perturbative methods. As µ decreases, the gauge
coupling increases, as described by the renormalization
group (RG) and associated beta function. To understand
the infrared (IR) properties of a strongly coupled chiral
gauge theory has long been, and continues to be, an outstanding goal in quantum field theory. If the theory satisfies the ’t Hooft global anomaly-matching conditions,
then it might confine and produce massless gauge-singlet
composite spin-1/2 fermions [1]-[10]. Alternatively, the
strong gauge interaction could produce bilinear fermion
condensates. A chiral gauge theory that does not contain
any vectorlike fermion subsector is defined as being irreducibly chiral. If a chiral gauge theory has an irreducibly
chiral fermion content, then these fermion condensates
necessarily break the chiral gauge symmetry [8, 10],[11][14], whereas if it contains a vectorlike fermion subsector,
then condensates of fermions in this vectorlike subsector may preserve the gauge symmetry. In both cases,
the fermion condensates break global chiral flavor symmetries. In general, there can be several stages of condensate formation at different momentum scales, with
a resultant sequence of gauge and/or global symmetry
breaking. Here and below, we restrict our consideration
to asymptotically free chiral gauge theories that have no
anomalies in gauged currents, as is required for renormalizability. Further, we restrict to theories with only gauge
and fermion fields but without any scalar fields.
There are several methods that one can use to investigate the ultraviolet to infrared evolution of a chiral gauge
theory. These include (i) (perturbative) calculation of
the beta function and analysis of possible IR zeros of
this beta function; (ii) use of the most-attractive-channel
(MAC) approach, which can suggest in which channel(s)
bilinear fermion condensates are most likely to form [12]
if the coupling gets sufficiently strong in the infrared; and
(iii) a conjectured inequality involving the perturbative
degrees of freedom in the massless fields [8, 15]. We will
denote this as the conjectured DFI, where DFI stands for
degree of freedom inequality. As was shown in [8] and discussed further in [9, 10], if the types of UV to IR evolution
involving either formation of fermion condensates with
associated spontaneous chiral gauge and global symmetry breaking or confinement with production of massless
composite fermions were to occur over a sufficiently large
range of fermion contents (specifically, a sufficiently large
range of values of p in the Sp model reviewed in Sect. III),
these would violate the conjectured degree-of-freedom inequality. Hence, assuming the validity of the conjectured
degree-of-freedom inequality imposes significant restrictions on the behaviors of these theories. Moreover, as
noted in [10], the type of UV to IR evolution that would
obey the degree-of-freedom inequality over the greatest
range of p values is not the one favored by the MAC approach. These results lead one to inquire whether it is
possible to achieve the goal of constructing chiral gauge
theories where the expected type(s) of UV to IR evolution obey the conjectured degree-of-freedom inequality
throughout the full range of parameters specifying the
fermion contents of these theories.
In this paper we report a successful achievement of this
goal and give several examples of such theories. Our theories have the gauge group SU(N ) and massless chiral
fermions transforming according to a symmetric rank-2
tensor representation of SU(N ), denoted S, and N + 4
copies (i.e., flavors) of a conjugate fundamental representation, denoted F¯ , together with a vectorlike subsector consisting of p copies of massless chiral fermions
in higher-dimensional representation(s). Because SU(2)
has only (pseudo)real representations, it does not yield a
chiral gauge theory, so we restrict our considerations to
chiral gauge theories having a gauge group SU(N ) with
N ≥ 3. We construct and analyze three theories of this
type. In the first two, the higher-dimensional represen-
Brane Gravitational Interactions
from 6D Supergravity
A. Salvio
arXiv:0909.0023v1 [hep-th] 31 Aug 2009
IFAE, Universitat Aut`
onoma de Barcelona,
08193 Bellaterra, Barcelona, Spain
Email: salvio@ifae.es
Abstract
We investigate the massive graviton contributions to 4D gravity in a
6D brane world scenario, whose bulk field content can include that of 6D
chiral gauged supergravity. We consider a general class of solutions having
3-branes, 4D Poincar´e symmetry and axisymmetry in the internal space.
We show that these contributions, which we compute analytically, can be
independent of the brane vacuum energy as a consequence of geometrical
and topological properties of the above-mentioned codimension two brane
world. These results support the idea that in such models the gravitational
interactions may be decoupled from the brane vacuum energy.
Keywords:
Field Theories in Higher Dimensions, Large Extra Dimensions, Supergravity models
PACS: 11.10.Kk, 04.50.-h, 11.25.Mj, 04.65.+e
1
Introduction
Higher dimensional theories offer new avenues to address longstanding fine tuning problems. Regarding the gauge hierarchy problem, there are now other possible solutions in addition to 4D supersymmetry, such as the Randall-Sundrum
[1, 2] and the Large Extra Dimensions scenario [3] (which requires, in its minimal formulation, at least two extra dimensions). Still the cosmological constant
problem remains an unsolved issue in theoretical physics.
A combination of the concepts of supersymmetry and (large) extra dimensions has been proposed [4] as a way to attack the cosmological constant problem, postulating two extra dimensions and codimension two 3-branes. Whether
this approach can be successful, it is still unclear (for criticisms and replies
see e.g. [5]-[6]), however, an interesting property of this scenario would be the
prediction of the Kaluza-Klein (KK) scale at 10−3 eV. One immediate consequence would be the onset of deviations from standard gravity at that scale,
which corresponds to the submillimeter. Thus, a natural question is whether
the matching with experimental and observational tests of gravity can impose
(additional) tuning of the brane tensions, once a 4D flat background solution is
chosen.
The aim of the present paper is to answer this question by considering a realization of 6D supergravity called the Salam-Sezgin model1 [8] (and its anomaly
free [9] extensions [10]). String theory derivations of this 6D supergravity have
1 For
an analysis of deviations from Newton’s law in different types of 6D supergravity see
[7].
1
Accidental symmetries and massless quarks in the economical
3-3-1 model
J. C. Montero∗
Instituto de F´ısica Te´orica, Universidade Estadual Paulista,
arXiv:1411.2580v1 [hep-ph] 10 Nov 2014
R. Dr. Bento Teobaldo Ferraz 271,
Barra Funda, SP, 01140-070, Brazil.
B. L. S´anchez–Vega†
Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439.
Abstract
In the framework of a 3-3-1 model with a minimal scalar sector, known as the economical 3-3-1
model, we study its capabilities of generating realistic quark masses. After a detailed study of the
symmetries of the model, before and after the spontaneous symmetry breaking, we find a remaining
axial symmetry that prevents some quarks to gain mass at all orders in perturbation theory. Since
this accidental symmetry is anomalous, we also consider briefly the possibility to generate their
masses for non-perturbative effects. However, we find that non-perturbative effects are not enough
to generate the measured masses for that three massless quarks. Hence, these results imply that
the economical 3-3-1 model is not a realistic description of the electroweak interaction and it has
to be modified.
PACS numbers: 12.15.Ff, 11.30.Fs, 11.15.Ex, 12.60.-i
∗
Electronic address: montero@ift.unesp.br
†
Electronic address: brucesanchez@anl.gov
1
Pions and excited scalars in Minkowski space DSBSE formalism
1, ∗
ˇ
V. Sauli
arXiv:1411.2568v1 [hep-ph] 10 Nov 2014
1
Department of Theoretical Physics, Institute of Nuclear Physics Rez near Prague, CAS, Czech Republic
We present the solution of Schwinger-Dyson and Bethe-Salpeter equation (BSE) for a light flawour non-singlet spinless meson in Minkowski space. The equations are solved in momentum space
without the use of the auxiliary Euclidean space. To exhibit that Minkowski space non perturbative
calculations are actually possible is the main purpose of presented paper. According to confinement,
the quark propagator is regular in momentum space, which allows us to look for the BSE solution
directly in the Minkowski momentum space. We find the Minkowski space solution for confining
theories is not only numerically accessible, but also provides a reasonable description of the pseudoscalar meson system. However, in the case of scalar mesons, the model is less reliable and we get
more extra light states then observed experimentally.
PACS numbers: 11.10.St, 11.15.Tk
I.
INTRODUCTION
Understanding of hadrons represents difficult tasks within the use of QCD degrees of freedom -quark and gluon
fields. In a more or less effective approaches including e.g. QCD sum rules, effective chiral Lagrangians, effective
Heavy quark methods, Hamiltonian light-cone approach, ADS/CFT correspondence etc. the problem is circumvented
by an additional, not always obviously satisfied, assumptions. On the other side, Lattice QCD as well as functional
Schwinger-Dyson equations (SDEs) in Euclidean space approximation (EA) are a conventional tool based on nonperturbative utilizing of quark and gluon degrees of freedom.
The last mentioned approaches should be equivalent when solved exactly and when vanishing lattice spacing is
achieved, at least when the both are defined in the auxiliary Euclidean space. For decades, it is largely believed that
the hadron spectra and related form factors for the timelike momenta should be feasible by an analytical continuation
of the real data originally calculated and collected in the Euclidean space. Recall, the region of timelike momenta
is just where the resonances ρ(n), ψ(n), Y (n)... exhibit variety of the peaks in a various form factors. In practice,
theorists have longstanding tremendous obstacles with an analytical continuation of Euclidean results to the Minkowski
space. Until now, neither the lattice nor the SDEs provide a form factor or cross section for the continuous timelike
arguments. The lattice has its on problems with the inclusion of the light quarks, while the EA Dyson-SchwingerBethe-Salpeter equations (DSBSEs) calculations show an incredible troubles due to the appearance of (complex
conjugated) singularities when QCD Green functions are evaluated at complex argument. For instance, in recent
DSBSEs treatment, this lead to the overlap of error bars for a different radial excitations in the light sector [1] as well
as in the sector of mesons made up from heavy quarks [2, 3]. A missing knowledge of propagators at complex momenta
makes a precise identification of energy levels impossible. Contrary, (not only) recent experiments do the best in the
timelike region, the electroproduction of hadrons represent one of the most precisely measured QCD process: the pion
form factor shows up unambiguous presence of rho like resonances, also five or six vector meson resonances are known
for charmonium and bottomonium with increasing energy of e+ e− pair.
In presented paper, the author ignores the conventional wisdom and does not follow historically prior suggestions
and do not solve the DSBSEs in the Euclidean space, but instead of, the calculations are performed directly in
Minkowski space. This somehow numerically inconvenient way, however leads to the results, which obviously are
not an analytical continuation of the Euclidean theory. The Greens functions become complex valued at the regime
where the Euclidean counter-partners must be real from the definition. Actually, we argue that this is phenomena
of confinement, which is responsible for such behavior and which also makes DSBSE system soluble directly in the
Minkowski momentum space. This simple fact has been overlooked or perhaps ignored by a community and to the
author knowledge, the first Minkowski space BSE solution has been shown for charmonium system [4] only very
recently. At this place one should also mention other Minkowski space BSEs solutions [5–10]. These methods are
based on Perturbation Theory Integral Representation (assuming validity of usual Wick rotation and positivity),
which perfectly fit for a weakly bounded system of particles. These methods do not contradict with EA results,
∗ Electronic
address: sauli@ujf.cas.cz
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–6
Updates of PDFs for the 2nd LHC run
Patrick Motylinskia,1 , Lucian Harland-Langa , Alan D. Martinb , Robert S. Thornea
a Department
arXiv:1411.2560v1 [hep-ph] 10 Nov 2014
b Institute
of Physics and Astronomy, University College London, WC1E 6BT, UK
for Particle Physics Phenomenology, Durham University, DH1 3LE, UK
Abstract
I present results on continuing updates in PDFs within the framework now called MMHT14 due to both theory
improvements and the inclusion of new data sets, including most of the up-to-date LHC data. A new set of PDFs is
essentially finalised, with no changes expected to the PDFs presented here.
It has been more than five years since the publication
of the global PDF analysis by MSTW titled ‘Parton
distributions for the LHC‘ [1]. Since then there have
been several significant improvements in the data, in
particular from the measurements made at the LHC,
and it appears to be time for an new global PDF
analysis within the previous MSTW08 (but now called
MMHT14) framework.
As new data have become available they have been
compared to the predictions provided by the MSTW
PDFs. In the process we continued to use the extended
parametrisation with Chebyshev polynomials as well
as the freedom in deuteron nuclear corrections [2].
This leads to a change in the uV − dV –distribution.
Furthermore, we use the optimal GM-VFNS choice [3]
with its increased smoothing near the heavy flavour
transition point. A small correction to the dimuon
production (ν + N → µ+ µ− ) has been taken into account
for the case where the charm quark is produced away
from the interaction point [4]. This has an impact,
albeit rather small, on the strange distribution. Furthermore, issues regarding the charm branching fraction
have been addressed. The value has been changed to
Bµ = 0.092 ± 10% from [5] where the uncertainty is
being fed into the PDFs. In the MMHT framework we
use the multiplicative definition of correlated uncertainties instead of additive [6]. This way the uncorrelated
errors effectively scale with the data.
1 Speaker.
1. Changes in data sets
We include new data that were officially published at
the end of 2013.
There has been several additions of non-LHC sets,
which should be mentioned here. The HERA run I
neutral- and charged current data from both HERA and
ZEUS have been replaced with a full combined set
with treatment of the correlated errors [7]. The HERA
combined data on the F2c (x, Q2 ) structure function have
been included [8]. Furthermore published HERA data
for F L (x, Q2 ) measurements have been included as
well [9]. It has been decided to wait with the inclusion
of Run II H1 and ZEUS until their combined data are
available.
A whole range of Tevatron data sets have been included:
CDF W–asymmetry data [10], D0 electron asymmetry
data (pT > 25GeV, 0.75fb−1 ) [11] and D0 muon asymmetry data (pT > 25GeV, 7.3fb−1 ) [12]. In addition,
the final numbers for CDF Z-rapidity data have been
taken into account [13]. Overall, the inclusion of the
mentioned sets do not have a major impact on the
PDFs. The impact on αS is rather moderate, too, with
it changing to αS = 0.1199 from αS = 0.1202 at NLO,
and changing to αS = 0.1181 from αS = 0.1171 at
NNLO.
Hadronic vacuum polarization function
within dispersive approach to QCD
A.V. Nesterenko∗
arXiv:1411.2554v1 [hep-ph] 10 Nov 2014
Bogoliubov Laboratory of Theoretical Physics,
Joint Institute for Nuclear Research,
Dubna, 141980, Russian Federation
The dispersive approach to QCD is applied to the study of the hadronic vacuum
polarization function Π(q 2 ). This approach provides unified integral representations
for Π(q 2 ) and related functions, which embody the intrinsically nonperturbative constraints originating in the kinematic restrictions on the respective physical processes.
The obtained hadronic vacuum polarization function proves to be in a good agreement with pertinent lattice simulation data. The calculated hadronic contributions
to the muon anomalous magnetic moment and to the shift of the electromagnetic
fine structure constant conform with recent estimations of these quantities.
PACS numbers: 11.55.Fv, 12.38.Lg, 13.40.Em, 14.60.Ef
I.
INTRODUCTION
The theoretical description of a number of the strong interaction processes is inherently
based on the hadronic vacuum polarization function Π(q 2 ). In particular, this function plays
a crucial role in the studies of the heaviest lepton hadronic decays and of the annihilation
of a pair of elementary particles into hadrons, that provides decisive self–consistency tests
of quantum chromodynamics (QCD). At the same time, the function Π(q 2 ) enters in the
analysis of the hadronic contributions to such quantities of the precise particle physics as the
muon anomalous magnetic moment and the running of the electromagnetic fine structure
constant, that, in turn, puts strong limits on the effects due to a possible new physics beyond
the standard model (SM). Additionally, the theoretical exploration of the aforementioned
processes constitutes a natural framework for a thorough investigation of both perturbative
and intrinsically nonperturbative aspects of hadron dynamics.
The strong interactions possess the feature of the asymptotic freedom, that makes it
possible to apply the perturbation theory to the study of the ultraviolet behavior of the
function Π(q 2 ). However, there is still no reliable method of theoretical description of hadron
dynamics at low energies, which would have provided one with rigorous unambiguous results.
This fact eventually forces one to invoke a variety of nonperturbative approaches in order
to examine the strong interactions in the infrared domain. For example, an insight into
the low–energy behavior of the hadronic vacuum polarization function can be gained from
such methods as lattice simulations [1–4], operator product expansion [5–8], as well as some
others (see, e.g., Refs. [9, 10]).
∗
nesterav@theor.jinr.ru
arXiv:1411.2485v1 [hep-ph] 10 Nov 2014
Meson mass splittings in unquenched quark models
(EEF70)∗
T. J. Burns†
Department of Mathematical Sciences, Durham University, DH1 3LE, UK
now at
Department of Physics, Swansea University, SA2 8PP, UK
General results are obtained for meson mass splittings and mixings in
unquenched (coupled-channel) quark models. Theorems derived previously
in perturbation theory are generalised to the full coupled-channel system.
A new formula is obtained for the mass splittings of physical states in
terms of the splittings of the valence states. The S-wave hyperfine splitting
decreases due to unquenching, but its relation to the vector e+ e− width is
unchanged; this yields a prediction for the missing ηb (3S). The ordinary
(quenched) quark model result that the P-wave hyperfine splitting vanishes
also survives unquenching. A ratio of mass splittings used to discriminate
quarkonium potential models is scarcely affected by unquenching.
1. Angular momentum coefficients
Unquenched quark models for meson spectroscopy incorporate qq pair
creation via the transition QQ → (Qq)(qQ). Most models have an operator
with the same basic structure, and so share the same general solution [1, 2]:
this applies to 3 P0 models, flux tube models (3 P0 and 3 S1 ), pseudoscalarmeson emission models, the Cornell model with Lorentz vector confinement
and, in the heavy-quark limit, more general microscopic models with Lorentz
scalar confinement and one-gluon exchange.
These “non-flip, triplet” models are characterised by the assumptions
that the initial Q and Q spins are conserved, and that the created qq pair
is coupled to spin triplet. The operator is a scalar product χ · O of a spin
triplet wavefunction χ (common to all models) and a spatial operator O
(which differs from model to model). The predictions of such models are
consistent with lattice QCD [3, 4].
∗
†
Presented at Workshop on Unquenched Hadron Spectroscopy: Non-Perturbative Models and Methods of QCD vs. Experiment (EEF70).
t.burns@oxon.org
(1)
6
proceedings
printed on November 11, 2014
Nevertheless future lattice calculations with (complete multiplets of)
(Qq)(qQ) operators could in principle offer a direct test of equation (10), if
spin splittings and Z-factors are measured at various quark masses. There is
already some work in this direction; Bali et al.[13] have measured splittings
and Z-factors for several charmonia, but at one quark mass and with one
(Qq)(qQ) operator per channel.
4. Conclusion
General results have been obtained for unquenched quak models based
on the non-flip, triplet operator. Previous results from perturbation theory, valid in the absence of spin splittings, have been generalised to the full
coupled-channel problem, and extended. The more realistic scenario, incorporating spin splittings among the valence and physical masses, involves a
simple mass formula, some of whose implications have been discussed here.
The formula ensures that several empirically successful results of quenched
quark models survive the effects of unquenching. The formula should be
testable in future lattice QCD calculations. Although it was not discussed
here, the formula is also useful for practical calculations of mass splittings
in unquenched quark models.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
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T. J. Burns, Phys.Rev. D90, 034009 (2014), 1403.7538.
T. J. Burns, (2013), 1311.3583.
T. J. Burns and F. E. Close, Phys. Rev. D74, 034003 (2006), hep-ph/0604161.
T. J. Burns, F. E. Close, and C. E. Thomas, Phys. Rev. D77, 034008 (2008),
0709.1816.
T. Barnes and E. Swanson, Phys.Rev. C77, 055206 (2008), 0711.2080.
Y. Kalashnikova, Phys.Rev. D72, 034010 (2005), hep-ph/0506270.
J.-F. Liu and G.-J. Ding, Eur.Phys.J. C72, 1981 (2012), 1105.0855.
T. J. Burns, Phys.Rev. D87, 034022 (2013), 1212.3250.
T. J. Burns, The Proceedings of “XIV International Conference on Hadron
Spectroscopy” (2011), 1108.5259.
T. J. Burns, Phys.Rev. D84, 034021 (2011), 1105.2533.
T. J. Burns, F. Piccinini, A. D. Polosa, and C. Sabelli, Phys. Rev. D82,
074003 (2010), 1008.0018.
C. E. Thomas, R. G. Edwards, and J. J. Dudek, Phys.Rev. D85, 014507
(2012), 1107.1930.
G. S. Bali, S. Collins, and C. Ehmann, Phys.Rev. D84, 094506 (2011),
1110.2381.
YITP-SB-14-43
Heavy Quarkonium Production at Collider Energies:
Partonic Cross Section and Polarization
Zhong-Bo Kang1 , Yan-Qing Ma2,3 , Jian-Wei Qiu4,5 , and George Sterman5∗
1
Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
arXiv:1411.2456v1 [hep-ph] 10 Nov 2014
2
Maryland Center for Fundamental Physics,
University of Maryland, College Park, MD 20742, USA
3
4
Center for High-Energy Physics, Peking University, Beijing, 100871, China
Physics Department, Brookhaven National Laboratory, Upton, NY 11973-5000, USA and
5
C.N. Yang Institute for Theoretical Physics and Department of Physics and Astronomy,
Stony Brook University, Stony Brook, NY 11794-3840, USA
(Dated: November 11, 2014)
Abstract
We calculate the O(α3s ) short-distance, QCD collinear-factorized coefficient functions for all partonic channels that include the production of a heavy quark pair at short distances. This provides
the first power correction to the collinear-factorized inclusive hadronic production of heavy quarkonia at large transverse momentum, pT , including the full leading-order perturbative contributions
to the production of heavy quark pairs in all color and spin states employed in NRQCD treatments of this process. We discuss the role of the first power correction in the production rates
and the polarizations of heavy quarkonia in high energy hadronic collisions. The consistency of
QCD collinear factorization and non-relativistic QCD factorization applied to heavy quarkonium
production is also discussed.
PACS numbers: 12.38.Bx, 13.88.+e, 12.39.-x, 12.39.St
∗
Electronic address: zkang@lanl.gov, yqma@bnl.gov, jqiu@bnl.gov, sterman@insti.physics.sunysb.edu
1
arXiv:1411.2430v1 [hep-ph] 10 Nov 2014
A Search of New Physics with
Ds+ → D +υυ, Bs0 → B 0υυ,
K + −→ π +υυ, D + −→ π +υυ, D + −→ π +υυ
and Ds+ −→ K +υυ
Shakeel Mahmood(1) ; Farida Tahir; Azeem Mir
Comsats Institute of Information Technology,
Department of Physics, Park Road, Chek Shazad,Islamabad
(1)
shakeel mahmood@hotmail.com
Abstract
We study rare decays
→ D+ υυ, Bs0 → B 0 υυ and K + −→ π + υυ in
the standard model as well as in NSIs. We calculate Branching ratios of
these decays. We revise the dependence of Ds+ → D+ υυ and K + −→
π + υυ these on free parameter ǫuL
τ τ and investigate the same dependence
on Bs0 → B 0 υυ.We show that there exist a possibility for ǫcL
τ τ .Three other
processes D+ −→ π + υυ, D+ −→ π + υυ and Ds+ −→ K + υυ are explored
with s quark in loop for NSIs instead of d quark. Constraints on ǫsL
τ τ and
′
ǫsL
ll′ (l, l 6= τ ) are provided. We point out that constraints from both u or
c quark and d or s are almost same.
PACS numbers: 12.60.-i, 13.15.+g, 13.20.-v
Ds+
1
Introduction
The effective Lagrangian for NSIs in model independent way is given in [1] and
can be written as
X fP
X fP
√
SI
LN
ǫαβ (ν α γµ Lνβ )(f γ µ P f ) +
ǫαβ (ν α γµ Lνβ )(f γ µ P f )
ef f = −2 2GF
α=β
α6=β
P
Here ǫfαβ
is the parameter for NSIs, which carries information about dynamics.
NSIs are thought to be well-matched with the oscillation effects along with new
features in neutrino searches [2][3][4][5][6][7][8]. Constraints on NSIs parameter
P
ǫfαβ
have been studied in References [9][10][11]. These are loop induced interactions in standard model (SM) and NSIs will affect neutral vertices only. From
scattering in leptonic sectors (f is lepton), constraints are determined for first
1
Universal description of radially
excited heavy and light vector mesons
S. S. Afonin and I. V. Pusenkov
arXiv:1411.2390v1 [hep-ph] 10 Nov 2014
V. A. Fock Department of Theoretical Physics, Saint-Petersburg State
University, 1 ul. Ulyanovskaya, St. Petersburg, 198504, Russia
Abstract
A new qualitative stringlike picture for mesons is proposed which
leads to a simple and intuitively clear generalization of linear radial
Regge trajectories to the case of massive quarks. The obtained universal relation is successfully tested in the sector of unflavored vector
mesons, where many radial excitations are known. Some new predictions are given. Our results suggest that the quark masses can be
easily estimated from the spectra of radially excited mesons.
1
Introduction
Starting from early times of the hadron spectroscopy it has been widely
believed that the dynamics responsible for the formation of hadrons is more
or less universal at all scales where the hadron resonances are observed. The
discovery of QCD provided a powerful support for this belief. Unfortunately,
QCD is still not amenable to analytical calculation of the hadron spectrum
and for this purpose one resorts to simplified dynamical models simulating
QCD. In practice, for description of the light and heavy hadrons, one exploits
usually different models. The main problem in the hadron spectroscopy,
however, is the building of a universal solvable model describing in detail the
whole meson or baryon spectrum as a function of quark masses. Despite a
great deal of interesting attempts (see, e.g., [1–3]), such a quantitative model
has not been constructed.
The question, then, is where should we look for the signs of universality? It is hardly believable that we can observe it in decay processes (in
decay width) which depend on the number of quark flavors and on the energy scale. But we may hope to find some interesting manifestations of the
universality in the mass spectrum of hadron states. Our hope is based on the
observation of approximately linear Regge, M 2 ∼ J, and linear radial Regge,
M 2 ∼ n, trajectories in the heavy mesons (see discussions in [4]). Here M
is the meson mass, J denotes the spin, and n means the radial quantum
number enumerating the daughter Regge trajectories. The point is that in
1
November 11, 2014
arXiv:1411.2372v1 [hep-ph] 10 Nov 2014
Theory and phenomenology of lepton flavor violation
Avelino Vicente
IFPA, Dep. AGO, Universit´e de Li`ege, Bat B5, Sart-Tilman B-4000 Li`ege 1,
Belgium
The field of lepton flavor violation will live an era of unprecedented
developments in the near future, with dedicated experiments in different
fronts. The observation of a flavor violating process involving charged
leptons would be a clear evidence of physics beyond the Standard Model,
thus motivating the great effort in this direction. Furthermore, in case a
positive signal is found, a proper theoretical understanding of the lepton
flavor anatomy of a given model would become necessary. Here I briefly
review the current situation, emphasizing the most relevant theoretical
and phenomenological aspects of several processes. Finally, I discuss two
topics that have received some attention recently: lepton flavor violation
in low-scale seesaw models and lepton flavor violating Higgs decays.
PRESENTED AT
8th International Workshop on the CKM Unitarity Triangle
(CKM 2014), Vienna, Austria, September 8-12, 2014
1
Introduction
The field of lepton flavor violation (LFV) is about to begin a golden era, with great
expectations in several experimental projects ∗ . In the coming years, many collaborations will join the search for LFV, currently led by the popular MEG experiment.
These new experiments will look for LFV in channels that not only include radiative
lepton decays, but also 3-body lepton decays (such as µ → 3 e), µ − e conversion in
nuclei or LFV in high-energy colliders. With these great perspectives, we may be
able to extend our knowledge on the physics beyond the Standard Model (SM) or, at
least, to significantly improve the current bounds.
On general grounds, one expects large LFV effects if new physics exists close to
the electroweak scale. In fact, most popular models predict large LFV rates. This
is easily understood by simple considerations based on effective field theory. Let us
consider the dim-6 operator
ceµ
Oeµ = 2 µeee ,
(1)
Λ
induced by some heavy degrees of freedom with masses of the order of Λ. It violates
the electron and muon flavors, thus inducing processes such as µ → 3 e. Using the
√
current bounds on this process one finds that the condition Λ/ ceµ > 100 TeV must
be satisfied. Therefore, if new physics capable of inducing the operator Oeµ is found at
the TeV scale, some suppression mechanism must be introduced in order to satisfy the
current LFV bounds. This, together with the promising experimental perspectives,
makes LFV an interesting road in the search for new physics, complementary to the
direct path based on high-energy colliders.
In case a positive observation in one or several experiments is made, the correct
interpretation of the results in a given model will definitely require a detailed understanding of its LFV anatomy. This theoretical effort should be ambitious. In addition
to detailed computations, patterns and correlations must be properly identified in order to be able to extract as much information as possible. Only by combining these
tests, typically valid for general classes of models, one can investigate the physics
responsible for LFV.
An example of one of these patterns is the so-called dipole dominance. In many
popular models, the operators with the dominant contributions to LFV processes are
dipole operators induced by photon exchange. This is for example the case of the
Minimal Supersymmetric Standard Model (MSSM). In this type of scenarios there
is a very strong correlation between radiative lepton decays and the corresponding
∗
See Section 1 of Ref. [1] and references therein for a complete review of the current experimental
situation and the future prospects.
1
Prog. Theor. Exp. Phys. 2013, 00000 (28 pages)
DOI: 10.1093/ptep/0000000000
Comprehensive analysis of the wave function of
a hadronic resonance and its compositeness
Takayasu Sekihara1,∗ Tetsuo Hyodo2 , and Daisuke Jido3
1
Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka, 567-0047, Japan
Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
3
Department of Physics, Tokyo Metropolitan University, Hachioji 192-0397, Japan
∗
E-mail: sekihara@rcnp.osaka-u.ac.jp
arXiv:1411.2308v1 [hep-ph] 10 Nov 2014
2
...............................................................................
We develop a theoretical framework to investigate the two-body composite structure of a
resonance as well as a bound state from its wave function. For this purpose, we introduce
both a one-body bare state and two-body scattering states, and define the compositeness
as the contribution from the two-body wave function to the normalization of the total
wave function. We explicitly write down the wave function and the compositeness for a
bound state obtained with a general separable interaction. In this formulation we can
derive the Weinberg’s relation for the scattering length and effective range in the weak
binding limit. Our discussion on the wave function is extended to a resonance state
expressed with the Gamow vector, and a relativistic formulation is also established. As
the applications, we study the compositeness of the Λ(1405) resonance and the light
scalar and vector mesons described with refined amplitudes in coupled-channel models
with interactions up to the next to leading order in chiral perturbation theory. We
¯ and K K
¯ composite states,
find that Λ(1405) and f0 (980) are dominated by the KN
∗
respectively, while the vector mesons ρ(770) and K (892) are elementary. We also briefly
discuss the compositeness of N (1535) and Λ(1670) obtained in a leading-order chiral
unitary approach.
1. Introduction
In hadron physics, the internal structure of an individual hadron is one of the most important
subjects. Traditionally, the excellent successes of constituent quark models lead us to the
interpretation that baryons consist of three quarks (qqq) and mesons of a quark-antiquark
pair (q q¯) [1]. At the same time, however, there are experimental indications that some
hadrons do not fit into the classification suggested by constituent quark models. One of the
classical examples is the hyperon resonance Λ(1405), which has an anomalously light mass
among the negative parity baryons. In addition, the lightest scalar mesons [f0 (500) = σ,
K0∗ (800) = κ, f0 (980), and a0 (980)] exhibit inverted spectrum from the na¨ıve expectation
with the q q¯ configuration. These observations motivate us to consider more exotic structure
of hadrons, such as hadronic molecules and multiquarks [2–7].
It is encouraging that there have been experimental reports on the candidates of manifestly
exotic hadrons such as Θ+ by LEPS collaboration [8, 9] and charged quarkonium-like states
by Belle collaboration [10]. The accumulation of the observations of unconventional states
in the heavy quark sector reinforces the existence of hadrons with exotic structure [11, 12].
In fact, recent detailed analyses of Λ(1405) in various reactions [13–16] and of the a00 (980)f0 (980) mixing in J/ψ decay [17] are providing some clues for unusual structure of these
c The Author(s) 2012. Published by Oxford University Press on behalf of the Physical Society of Japan.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License
(http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
New bounds on neutrino electric millicharge from
GEMMA experiment on neutrino magnetic moment
arXiv:1411.2279v1 [hep-ph] 9 Nov 2014
Victor B. Brudaninb , Dmitry V. Medvedevb , Alexander S. Starostinc ,
Alexander I. Studenikina,b
a
Department of Theoretical Physics, Faculty of Physics, Moscow State University,
Moscow 119991, Russia
b
Joint Institute for Nuclear Research, Dubna 141980, Moscow Region, Russia
c
Institute for Theoretical and Experimental Physics, National Research Centre
”Kurchatovsky Institute”, B.Cheremushkinskaya 25, 117218 Moscow, Russia
Abstract
Using the new limit on the neutrino anomalous magnetic moment recently
obtained by GEMMA experiment we get an order-of-magnitude estimation
for possible new direct upper bound on the neutrino electric millicharge
| qν |∼ 1.5 × 10−12 e0 (e0 is the absolute value of the electron charge) by
comparing the neutrino magnetic moment and millicharge contributions to
the total cross section at the electron recoil energy threshold of the experiment. This estimation is confirmed by the performed analysis of the GEMMA
data using established statistical procedures and a new direct bound on the
neutrino millicharge absolute value | qν |< 2.7 × 10−12 e0 (90%CL) is derived. This limit is more stringent than the previous one obtained from the
TEXONO reactor experiment data that is included to the Review of Particle
Properties 2012.
Keywords:
1. Introduction
The importance of neutrino electromagnetic properties was first mentioned by Wolfgang Pauli just in 1930 when he postulated the existence of this
Email addresses: brudanin@jinr.ru (Victor B. Brudanin), chess1984@mail.ru
(Dmitry V. Medvedev), starostin@itep.ru (Alexander S. Starostin),
studenik@srd.sinp.msu.ru (Alexander I. Studenikin)
Preprint submitted to Elsevier
November 11, 2014
Discovering the QCD Axion with Black Holes and Gravitational Waves
Asimina Arvanitaki,∗
Perimeter Institute for Theoretical Physics, Waterloo, Ontario, N2L 2Y5, Canada
Masha Baryakhtar,† and Xinlu Huang,‡
arXiv:1411.2263v1 [hep-ph] 9 Nov 2014
Stanford Institute for Theoretical Physics, Department of Physics,
Stanford University, Stanford, CA 94305, USA
(Dated: November 11, 2014)
Advanced LIGO will be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with
decay constant above the GUT scale. When an axion’s Compton wavelength is comparable to the
size of a black hole, the axion binds to the black hole, forming a “gravitational atom.” Through
the superradiance process, the number of axions occupying the bound levels grows exponentially,
extracting energy and angular momentum from the black hole. Axions transitioning between levels of the gravitational atom and axions annihilating to gravitons produce observable gravitational
wave signals. The signals are long-lasting, monochromatic, and can be distinguished from ordinary
astrophysical sources. We estimate O(1) transition events at aLIGO for an axion between 10−11
and 10−10 eV and up to 1000 annihilation events for an axion between 10−13 and 10−12 eV. Axion
annihilations are particularly promising for much lighter masses at future lower-frequency gravitational wave observatories, where we expect as many as 105 events. Our results are robust against
perturbations from the black hole environment and account for our updated exclusion on the QCD
axion of 6 × 10−13 eV < µa < 1.5 × 10−11 eV suggested by stellar black hole spin measurements.
I.
CONTENTS
I
What is Superradiance?
II Theoretical Background
A. The Gravitational Atom in the Sky
B. A (Not So) Brief History of Superradiance
1
3
3
4
III Gravitational Wave Signals
A. Level Transitions
1. Advanced LIGO/VIRGO Prospects
2. Future Gravitational Wave Observatories
B. Annihilations
1. Advanced LIGO/VIRGO Prospects
2. Future Gravitational Wave Observatories
C. Bosenovae
5
6
7
9
9
10
11
12
IV Bounds from Black Hole Spin Measurements
12
V Effect of the Black Hole Environment
A. Companion Star
B. Accretion Disk
14
15
15
VI Summary
16
A Gravitational Wave Power Calculation
17
B Event Rate Calculation
18
∗
†
‡
aarvanitaki@perimeterinstitute.ca
mbaryakh@stanford.edu
xinluh@stanford.edu
WHAT IS SUPERRADIANCE?
A wave that scatters from a rotating black hole can
exit the black hole environment with a larger amplitude
than the one with which it came in. This amplification
happens for both matter and light waves, both fermions
and bosons, and it is called black hole superradiance. It
is an effect that has been known for nearly 50 years [1].
Massive bosonic waves are special. They form bound
states with the black hole whose occupation number can
grow exponentially [2]; for fermions, Pauli’s exclusion
principle makes this lasing effect impossible. This exponential growth is understood if one considers the mass
of the boson acting as a mirror that forces the wave to
confine in the black hole’s vicinity and to scatter and
superradiate continuously. This is known as the superradiance (SR) instability for a Kerr black hole and is an
efficient method of extracting angular momentum and
energy from the black hole. Rapidly spinning astrophysical black holes thus become a diagnostic tool for the
existence of light massive bosons [3, 4].
Black hole superradiance sounds exotic and mysterious since it naively appears to be deeply connected
with non-linear gravitational effects in the vicinity of
black holes. Instead, superradiance is a purely kinematic effect, and black hole superradiance is just another manifestation of the superradiance phenomenon
that appears in a variety of systems. The most famous is inertial motion superradiance, most commonly
referred to as Cherenkov radiation [5]. In Cherenkov
radiation, a non-accelerating charged particle spontaneously emits radiation while moving superluminally in a
medium. The emitted radiation forms a cone with opening angle cos θ = (nv)−1 , where n is the index of refrac-
New predictions on the mass of the 1−+ light hybrid meson from QCD sum rules
1
Zhuo-Ran Huang1 , Hong-Ying Jin1 and Zhu-Feng Zhang2
Zhejiang Institute of Modern Physics, Zhejiang University, Zhejiang Province, P. R. China
2
Physics Department, Ningbo University, Zhejiang Province, P. R. China
arXiv:1411.2224v1 [hep-ph] 9 Nov 2014
We calculate the coefficients of the dimension-8 quark and gluon condensates in the current-current
correlator of 1−+ light hybrid current g q¯(x)γν iGµν (x)q(x). With inclusion of these higher-power
corrections and updating the phenomenological input parameters, we re-extract the mass of the
1−+ light hybrid meson from QCD sum rules. By using the Monte-Carlo based matching method,
we obtain a mass prediction around 2.26 GeV, which is significantly larger than previous QCDSR
predictions and suggests that π1 (2015) is a better hybrid candidate compared with π1 (1600) and
π1 (1400).
PACS numbers: 12.38.Lg, 12.39.Mk, 14.40.Rt
I.
INTRODUCTION
Mesons with exotic quantum numbers have long been attractive in hadron physics, among which are the J P C = 1−+
isovector states π1 (1400) , π1 (1600) and π1 (2015) identified in the experiments [1]. The construction of these states are
not quite clear, four-quark states and hybrid states are most possible explanations. Theoretical studies via different
methods have shown that some of these states can be considered as good light hybrid candidates. In the bag model,
the predicted mass of 1−+ light hybrid meson is around 1.5 GeV[2]; the mass from the flux tube model is found to be
in the range 1.7–1.9 GeV [3]; the lattice QCD prediction of 1−+ mass is 1.9–2.2 GeV [4]. Calculations based on QCD
sum rules [5] have been conducted by different groups [6–9] to NLO of d ≦ 6 contributions, and the latest versions
of the predicted mass are 1.80 ± 0.06 GeV in [10] and 1.71 ± 0.22 GeV in [11]. Although the hybrid explanation for
π1 (1600) is supported by the previous sum rule analysis, the hybrid assignment of π1 (2015) is also proposed [10].
Thus the calculation of higher power corrections (HPC) of the OPE is interesting and of value. How and how much
the HPC affect the mass prediction would lead to totally different conclusions.
In this paper, we focus on the mass prediction of the 1−+ light hybrid meson using QCD sum rule method.Dimension8 contributions will be taken into account, and we will use the least-square method to fit the sum rules following
Leiweber’s procedure [12]. For the explicit consideration of higher power corrections is not seen very often in previous
sum rule calculations, we will give a slightly more detailed presentation of our calculation and analysis.
II.
OPE FOR THE CURRENT-CURRENT CORRELATOR
We start from the two-point correlator
Πµν (q 2 ) = i
Z
d4 xeiqx 0 T jµ (x)jν+ (0) 0
(1)
= (qµ qν − q 2 gµν )Πv (q 2 ) + qµ qν Πs (q 2 )
where jµ (x) = g q¯(x)γν iGµν (x)q(x), and the invariants Πv (q 2 ) and Πs (q 2 ) correspond respectively to 1−+ and 0++
contributions.
The correlator obeys the standard dispersion relation
Z
1 ∞ ImΠv/s (s)
Πv/s (q 2 ) =
.
(2)
ds
π 0
s − q 2 − iǫ
In this paper, we focus on the dimension-8 corrections to the 1−+ mass. Before showing the higher power results we
need to mention that coefficients of dimension-8 quark-related operators of the 1−+ light hybrid two-point correlator
have been calculated in [6] and [7]. In [6] there is only a factorized form of the total result and a complete result is
given in [7]. We obtain a new complete result which is consistent with the former factorized form but different from
the latter one.
As for dimension-8 gluon operators, there arise IR divergences in the calculation of the quark loops as the result of
setting mq = 0 before calculating the integrals. These IR divergences can be canceled after taking operator mixing
into account. This process can partly check the calculation about dimension-8 quark and gluon operators and modify
arXiv:1411.2218v1 [hep-ph] 9 Nov 2014
A pseudoscalar glueball and charmed mesons in the extended
Linear Sigma Model ∗
Walaa I. Eshraim
Institute for Theoretical Physics,
Johann Wolfgang Goethe University,
Max-von-Laue-Str. 1, D-60438 Frankfurt am Main, Germany
November 11, 2014
Abstract
In the framework of the so-called extended linear sigma model (eLSM), we include a pseudoscalar glueball with a mass of 2.6 GeV (as predicted by Lattice-QCD simulations) and we
compute the two- and three-body decays into scalar and pseudoscalar mesons. This study is relevant for the future PANDA experiment at the FAIR facility. As a second step, we extend the
eLSM by including the charm quark according to the global U (4)R × U (4)L chiral symmetry. We
compute the masses, weak decay constants and strong decay widths of open charmed mesons. The
precise description of the decays of open charmed states is important for the CBM experiment at
FAIR.
1
Introduction
The fundamental interactions of quarks and gluons are described by quantum chromodynamics (QCD).
The development of an effective hadronic Lagrangian plays an important role in the description of the
masses and the interactions of low-lying hadron resonances [1]. To this end, we developed the so-called
extended Linear Sigma Model (eLSM) [2] in which (pseudo)scalar and (axial-)vector qq mesons and
additional scalar and pseudoscalar glueball fields are the basic degrees of freedom. The eLSM emulates
the global symmetries of the QCD Lagrangian: the global chiral symmetry (which is exact in the
chiral limit), the discrete C, P, and T symmetries, and the classical dilatation (scale) symmetry. When
working with colorless hadronic degrees of freedom, the local color symmetry of QCD is automatically
preserved. In QCD (and thus also in the eLSM) the global chiral symmetry is explicitly broken by nonvanishing quark masses and quantum effects [4], and spontaneously by a non-vanishing expectation
value of the quark condensate in vacuum [5]. The dilatation symmetry is broken explicitly by the
logarithmic term of the dilaton potential, by the mass terms, and by the U (1)A anomaly.
The investigation of the properties of bound states of gluons, so-called glueballs, is an important
field of research in hadronic physics. The glueball spectrum has been predicted by Lattice QCD [6],
e ≡ gg, with a mass
where the third lightest glueball is a pseudoscalar state (J P C = 0−+ ), denoted as G
of about 2.6 GeV, which is studied in the present work.
Studying the properties of the third most massive of all quarks, the charm quark, is an active
field of hadronic physics [7]. Thus we extend the eLSM (which has shown success in describing the
phenomenology of the nonstrange-strange mesons [2, 8]) from the three quark-flavor case [8] to the
four quark-flavor case [9, 10, 11] with only three new unknown parameters related to the charm sector.
∗ Presented at the 3rd International Conference on New Frontiers in Physics, 28th July - 6th August 2014, Kolymbari,
Crete, Greece.
1
Few-Body Systems manuscript No.
(will be inserted by the editor)
T. J. Hobbs
arXiv:1411.2216v1 [hep-ph] 9 Nov 2014
Phenomenological implications of the nucleon’s
meson cloud
Received: date / Accepted: date
Abstract The long-distance structure of the interacting nucleon receives important contributions
from its couplings to light hadronic degrees of freedom — a light meson cloud — while an analogous
nonperturbative mechanism is expected to generate an intrinsic charm (IC) component to the proton
wavefunction. We investigate both possibilities, keeping for the former a special eye to improving the
theoretical understanding of the pion-nucleon vertex in light of proposed measurements. Regarding the
latter possibility of IC, we highlight recent results obtained by a global QCD analysis of the light-front
model proposed in Ref. [1].
Keywords quark models · heavy quarks · effective field theory · deeply inelastic scattering
1 Introduction
As much as a desire to understand bound state properties of hadrons motivated the development of
QCD, efforts based solely upon perturbative QCD remain stubbornly unyielding toward a thorough
grasp of long-range hadronic structure. The defining reason has much to do with the fact that nonperturbative mechanisms are decisive in shaping various aspects of the makeup and internal dynamics of
hadrons. That this must be the case is evident, for instance, in the role played by light pionic modes
in qualitatively shaping the peripheral charge distribution of the nucleon due to pion-nucleon loop
corrections at its electromagnetic vertex. Such corrections are a direct consequence of the nucleon’s
pion cloud — essentially, a dressing of the nucleon wavefunction by short-lived configurations of virtual SU (2) mesons, of which the pion as the lightest mode is expected to dominate at small momenta
(. 500 MeV). In fact, at small values of the t-channel exchange mass (t ∼ m2π ) the presence of the
pion cloud provides a natural description of the electron-nucleon DIS interaction in terms of spontaneous dissociations of the form N → πN under the constrains of, e.g., charge conservation and gauge
invariance.
The existence of the pion cloud is in principle well-established by a substantial body of exper¯
imental measurements and theoretical analyses (e.g., of light quark sea asymmetries [¯
u − d](x)
6= 0
relevant to Gottfried Sum Rule violation). At the same time, the detailed momentum dependence of the
pion-nucleon vertex remains a significant source of model dependence in any effort at first-principles
calculation; proposed DIS extractions of the pion structure function (SF) F2π (x, Q2 ) at the crucial pion
mass pole t = m2π depend upon sensitivity to mechanisms including those depicted in Fig. 1 for which
This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of
Basic Energy Sciences program under Award Number DE-FG02-97ER-41014.
T. J. Hobbs
Department of Physics, University of Washington, Seattle, WA 98195-1560
Tel.: +1-206-543-9754
E-mail: tjhobbs@uw.edu
Dark matter in the hidden gauge theory
Nodoka Yamanaka1 ,∗ Sho Fujibayashi2 , Shinya Gongyo2,3 , and Hideaki Iida2
1
iTHES Research Group, RIKEN, Wako, Saitama 351-0198, Japan
Department of Physics, Graduate School of Science, Kyoto University,
Kitashirakawa-oiwake, Sakyo, Kyoto 606-8502, Japan and
3
Department of Physics, New York University, New York, 10003, USA
(Dated: November 11, 2014)
arXiv:1411.2172v1 [hep-ph] 8 Nov 2014
2
The cosmological scenario of the dark matter generated in the hidden gauge theory based on the
grand unification is discussed. It is found that the stability of the dark matter halo of our Galaxy and
the cosmic ray observation constrain, respectively, the dark matter mass and the unification scale
between the standard model and the hidden gauge theory sectors. To obtain a phenomenologically
consistent thermal evolution, the entropy of the standard model sector needs to be increased. We
therefore propose a scenario where the mini-inflation is induced from the potential coupled to the
Standard model sector, in particular the Higgs sector. This scenario makes consistent the current
dark matter density as well as the baryon-to-photon ratio for the case of pion dark matter. For the
glueball or heavy pion of hidden gauge theory, an additional mini-inflation in the standard model
sector before the leptogenesis is required. We also propose the possibility to confirm this scenario
by known prospective experimental approaches.
PACS numbers: 98.80.-k,95.35.+d,11.15.-q,98.80.Cq
From recent observations, it is now known that 27% of
the energy of our Universe is composed of dark matter
(DM) [1]. The presence of it was also indicated by many
previous observations [2–4], and the result of the N-body
simulation suggests that this medium forms nonrelativistic clusters [5], which explains the DM halo surrounding
our Galaxy. We currently believe that this halo is indispensable for the formation of stars and galaxies that we
can observe today [6], and consequently for the origin of
the life and our existence. The investigation of the origin
of the DM is thus one of the most essential subject.
Currently, the DM is known to be composed of weakly
interacting massive particles [7]. However, it is also currently known that there are no candidates of DM particles in the standard model (SM) of particle physics. We
therefore need to introduce a new extended theory beyond the SM to explain the DM [8–13]. Here we would
like to investigate a natural scenario for the inclusion of
the DM by postulating the existence of new gauge forces
which are unified at the fundamental scale but decoupled with the visible sector. This hidden gauge theory
(HGT) presents many strong advantages in the pointof-view of the naturalness: 1) The fundamental interactions are unified at some high energy scale, like the commonly believed grand unified theory (GUT) of the SM
sector [14], and this fact allows the existence of many
gauge interactions out of the SM sector. Moreover, this
high energy scale guaranties the weak correlation with
the SM sector. 2) The mass scales of the gauge theory
are controlled by the color and flavor numbers through
the running coupling, so that the theory does not involve
a serious hierarchical problem. 3) The lightest particles
are DM hadrons, so they can be natural candidates of
DM component, although being self-interacting [15–20].
In this letter, we discuss the DM generated by the ad-
ditional hidden SU (Nc ) gauge theory which is unified
with the SM sector at some GUT scale. We first examine the cosmological dynamics of the HGT and the
phenomenological constraints on it. We then propose a
new scenario requiring mini-inflations to consistently implement the HGT into the cosmology. The prospective
approaches to confirm this scenario are finally given. In
this work, we do not discuss the mechanism for generating the gauge theories at the GUT scale. We only consider SU (Nc ) gauge theories with Nf fermions, without
any scalar bosons and supersymmetry [20].
In this work, we assume the SU (Nc ) HGT with Nf
equal mass fermions. This nonabelian gauge theory dynamically generates a mass scale ΛDM . In the HGT, the
lightest particle is a pion if there is at least one quark
lighter than the scale parameter ΛDM , or a glueball if
there are no quarks lighter than ΛDM [19]. From a simple dimensional analysis, the mass of the DM glueballs,
mφ , and that of the DM pions, mπ , in the SU (Nc ) gauge
theory are respectively given by
q
p
1
mq h0|¯
q q|0i ∼ mq ΛDM , (1)
mφ ∼ ΛDM , mπ =
fDM
where fDM and h0|¯
q q|0i are, respectively, the pion decay constant and the chiral condensate, which is approximated to be equal to ΛDM and Λ3DM .
We first see the constraint on the scale of unification
between the SM and the HGT. As the HGT and the SM
are unified at ΛGUT , DM particles interact with SM particles through gauge bosons with mass of O(ΛGUT ). The
clearest way to find the unification scale is to directly test
the production of DM via the accelerator [21] or direct
DM detection experiments [22]. These set a constraint of
ΛGUT > O(TeV) for mDM < O(TeV). The most sensitive
approach to ΛGUT is the indirect detection experiments
arXiv:1411.2162v1 [hep-ph] 8 Nov 2014
Differences between Axions and Generic Light
Scalars in Laboratory Experiments
Sonny Mantry1∗, Mario Pitschmann2 and Michael J. Ramsey-Musolf3,4
1
Department of Physics, University of North Georgia, Dahlonega, GA, USA
Institute of Atomic and Subatomic Physics, Vienna University of Technology, Vienna
3
Amherst Center for Fundamental Interactions, Department of Physics, University of Massachussetts Amherst, Amherst, MA, USA
4
California Institute of Technology, Pasadena, CA, USA
2
It is well-known that electric dipole moment (EDM) constraints provide the most stringent
bounds on axion-mediated macroscopic spin-dependent (SD) and time reversal and parity
violating (TVPV) forces. These bounds are several orders of magnitude stronger than
those arising from direct searches in fifth-force experiments and combining astrophysical
bounds on stellar energy loss with E¨
otv¨
os tests of the weak equivalence principle (WEP).
This is a consequence of the specific properties of the axion, invoked to solve the Strong
CP problem. However, the situation is quite different for generic light scalars that are
unrelated to the strong CP problem. In this case, bounds from fifth-force experiments and
astrophysical processes are far more stringent than the EDM bounds, for the mass range
explored in direct searches.
In this work [1], we consider the nature of constraints on macroscopic spin-dependent (SD)
and T- and P-violating (TVPV) forces mediated by light scalar particles. In particular, we focus
on differences between forces mediated by axions that solve the Strong CP problem and generic
scalars that are unrelated to the Strong CP problem. Here macroscopic forces are understood
to have an interaction range r 1 ˚
A. For example, such a force can arise at the microscopic
level through a coupling of a light scalar ϕ with the light quarks q = u, d
Lϕqq = ϕ q¯ gsq + igpq γ 5 q ,
(1)
which in turn can induce nucleon level couplings
LϕN N
=
¯ gs + igp γ 5 N
ϕN
,
(2)
q
where the nucleon-level couplings gs,p are related to the quark level couplings gs,p
via nuclear
matrix elements as determined by a matching calculation. For simplicity, we have assumed
u
d
isoscalar couplings so that gs,p
= gs,p
and ignored possible couplings to leptons. Such interactions give rise to a nucleon-nucleon monopole-dipole potential in the non-relativistic limit that
has the form [2]
V (r)
∗ Speaker
= gs gp
1
~σ2 · rˆ mϕ
+ 2 e−mϕ r
8πM2 r
r
,
(3)
at the 10th PATRAS Workshop on Axions, WIMPs, and WISPs, 2014, CERN, Geneva, Switzerland.
Patras 2014
1
November 11, 2014 1:25 WSPC/INSTRUCTION FILE
IEDMmpla
arXiv:1411.2150v1 [hep-ph] 8 Nov 2014
Modern Physics Letters A
c World Scientific Publishing Company
INTRODUCTION TO THE SPECIAL ISSUE
”INDIRECT DARK MATTER SEARCHES”.
MAXIM YU. KHLOPOV
National Research Nuclear University ”MEPHI” (Moscow Engineering Physics Institute) and
Centre for Cosmoparticle Physics ”Cosmion” 115409 Moscow, Russia
APC laboratory 10, rue Alice Domon et L´
eonie Duquet
75205 Paris Cedex 13, France
khlopov@apc.univ-paris7.fr
Received (Day Month Year)
Revised (Day Month Year)
The nature of cosmological dark matter finds its explanation in physics beyond the Standard model of elementary particles. The landscape of dark matter candidates contains a
wide variety of species, either elusive or hardly detectable in direct experimental searches.
Even in case, when such searches are possible the interpretation of their results implies
additional sources of information, which provide indirect effects of dark matter. Some
nontrivial probes for the nature of the dark matter are presented in the present issue.
Keywords: Elementary particles; dark matter; early universe; primordial black holes, axions; axion-like particles; decaying dark matter, dark matter annihilation, mirror matter,
shadow matter, Weakly Interacting Massive Particles, large-scale structure of universe;
cosmic rays, gamma radiation.
PACS Nos.: include PACS Nos.
Cosmological dark matter is the important basic element of our current understanding of the structure and evolution of the Universe. It cannot be explained by
the known forms of matter and implies physics beyond the Standard model of elementary particles for its description. The list of dark matter candidates, predicted
by the extensions of the Standard model, is so wide that can be hardly covered in an
issue like that. Still rather wide range of possibilities is considered here: primordial
black holes, axions and axion-like particles, decaying, annihilating and composite
dark matter. Various candidates imply different ways to probe their existence and
there is no need to repeat in this Introduction the content of the contributions to
the present issue. Instead we’d like here to give a brief review of the general frame of
the fundamental relationship of macro- and micro worlds, in which indirect effects
of dark matter play important role.
The problem of dark matter, corresponding to ∼ 25% of the total cosmological density, involves two aspects, in which physics beyond the standard model of
elementary particles is involved. The dark matter species (see e.g.1,2,3,4 for review
and reference) should be stable, saturate the measured dark matter density and
1
arXiv:1411.2137v1 [hep-ph] 8 Nov 2014
The 3 flavor NJL with explicit symmetry breaking
interactions: scalar and pseudoscalar spectra and decays.∗
A. A. O SIPOV, B. H ILLER , A. H. B LIN
Departamento de Física, CFC, Faculdade de Ciências e Tecnologia da Universidade de
Coimbra, P-3140-308 Coimbra, Portugal
The effective quark interactions that break explicitly the chiral SU (3)L ×
SU (3)R and UA (1) symmetries by current-quark mass source terms are considered in NLO in Nc counting. They are of the same order as the ’t Hooft flavor
determinant and the eight quark interactions that extend the LO Nambu-JonaLasinio Lagrangian, and complete the set of non-derivative and spin 0 interactions relevant for the Nc scheme. The bosonized Lagrangian at meson tree level
describes accurately the empirical ordering and magnitude of the splitting of states
in the low lying pseudoscalar and scalar meson nonets, for which the explicit symmetry breaking terms turn out to be essential. The strong interaction and radiative
decays of the scalar mesons are understood in terms of the underlying microscopic
multi-quark states, which are probed differently by the strong and the electromagnetic interactions. We also obtain that the anomalous two photon decays of the
pseudoscalars are in very good agreement with data.
PACS numbers: PACS: 11.30.Rd; 11.30.Qc; 12.39.Fe; 12.40.Yx
Effective low energy Lagrangians of QCD are operational at the scale of spontaneous breaking of chiral symmetry, of the order of ΛχSB ∼ 4πfπ [1]. In the
Nambu-Jona-Lasinio (NJL) model [2] this scale is also related to the gap equation
and given by the ultra-violet cutoff Λ of the one-loop quark integral, above which
one expects non-perturbative effects to be of less importance. We consider in our
Lagrangian [3, 4] generic vertices Li of non-derivative type that contribute to the
effective potential as Λ → ∞
Li ∼
∗
g¯i α β
χ Σ ,
Λγ
(1)
Presented at the workshop "Eef70" on Unquenched Hadron Spectoscopy: Non-Perturbative
Models and Methods of QCD vs. Experiment, 01-05 September 2014 in Coimbra, Portugal.
Work supported by Centro de Física Computacional (CFC) da Universidade de Coimbra. Part
of the EU Research Infrastructure Integrating Activity Study of Strongly Interacting Matter
(HadronPhysics3) under the 7th Framework Programme of EU: Grant Agreement No. 283286.
(1)
Nuclear Physics B
Proceedings
Supplement
Nuclear Physics B Proceedings Supplement 00 (2014) 1–6
Complementarity of direct and indirect searches in the pMSSMI
Farvah Mahmoudi, Alexandre Arbey
arXiv:1411.2128v1 [hep-ph] 8 Nov 2014
Universit´e de Lyon, Universit´e Lyon 1, F-69622 Villeurbanne Cedex, France;
Centre de Recherche Astrophysique de Lyon, Saint Genis Laval Cedex, F-69561, France;
CNRS, UMR 5574; Ecole Normale Sup´erieure de Lyon, France
CERN Theory Division, Physics Department, CH-1211 Geneva 23, Switzerland
Abstract
We explore the pMSSM parameter space in view of the constraints from SUSY and monojet searches at the LHC,
from Higgs data and flavour physics observables, as well as from dark matter searches. We show that whilst the
simplest SUSY scenarios are already ruled out, there are still many possibilities left over in the pMSSM. We discuss
the complementarity between different searches and consistency checks which are essential in probing the pMSSM
and will be even more important in the near future with the next round of data becoming available.
1. Introduction
Data from the first run of the LHC and from dark
matter (DM) direct detection experiments provide us already with important constraints on the supersymmetric parameter space. We consider the phenomenological MSSM (pMSSM), which is the most general MSSM
set-up with R-parity and CP conservation respecting the
minimal flavour violation (MFV) paradigm. With its
19 independent parameters, the pMSSM offers sufficient freedom to the masses and couplings to explore
the supersymmetric parameter space and the implications of the recent particle and astroparticle physics
data in a largely unbiased way. The 19 parameters are
scanned over in the ranges given in Table 1 following
the methodology described in Refs. [1, 2].
The SUSY mass spectra and decay branching fractions are computed using SOFTSUSY [3], HDECAY
[4] and SDECAY [5]. The Higgs boson production
rates are calculated with HIGLU [6], bbh@nnlo [7] and
I Based on the talk by F.M. at the Fifth Capri Workshop on the
interplay of flavour physics with electroweak symmetry breaking and
dark matter, Capri, May 2014.
Email addresses: nazila@cern.ch (Farvah Mahmoudi),
alexandre.arbey@ens-lyon.fr (Alexandre Arbey)
Parameter
tan β
MA
M1
M2
M3
Ad = A s = Ab
Au = Ac = At
Ae = Aµ = Aτ
µ
Me˜ L = Mµ˜ L
Me˜R = Mµ˜ R
Mτ˜ L
Mτ˜ R
Mq˜ 1L = Mq˜ 2L
Mq˜ 3L
Mu˜ R = Mc˜R
Mt˜R
Md˜R = M s˜R
Mb˜ R
Range (in GeV)
[1, 60]
[50, 2000]
[-3000, 3000]
[-3000, 3000]
[50, 3000]
[-10000, 10000]
[-10000, 10000]
[-10000, 10000]
[-3000, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
[0, 3000]
Table 1: pMSSM scan ranges.
Non-uniform phases in a three-flavour ’t Hooft extended
Nambu-Jona–Lasinio model∗
arXiv:1411.2126v1 [hep-ph] 8 Nov 2014
J. Moreira, B. Hiller,
Centro de F´ısica Computacional, Department of Physics,
University of Coimbra, P-3004-516 Coimbra, Portugal
W. Broniowski,
The H. Niewodnicza´
nski Institute of Nuclear Physics,
Polish Academy of Sciences, PL-31342 Krak´ow, Poland
Institute of Physics, Jan Kochanowski University, PL-25406 Kielce, Poland
A. A. Osipov, A. H. Blin
Centro de F´ısica Computacional, Department of Physics,
University of Coimbra, P-3004-516 Coimbra, Portugal
The possible existence of non-uniform phases in cold dense quark matter
in the light quark sector (u, d and s) is addressed using the Nambu-Jona–
Lasinio Model extended to include flavour-mixing ’t Hooft determinant.
The effect of changes in the coupling strengths of the model is discussed.
It is seen that the inclusion of the strange sector catalyses the appearance
of these non-uniform phases extending the domain for their appearance.
PACS numbers: 11.30.Rd, 11.30.Qc, 12.39.Fe, 21.65.Qr
1. Introduction
Due to the attractive nature of the pionic interaction with quarks (or
nucleons) when the mean pion field carries a gradient, it has long ago been
proposed (for a recent historical review see, for instance, [1]) that the nontrivial dynamics between this attractive effect and that of the kinetic terms
could allow for the existence of non-uniform phases in the low temperature,
high chemical potential regime. As the sign problem affects the more fundamental approach of lattice QCD, the use of alternative approaches such as
low energy models of the Nambu–Jona-Lasinio (NJL) [2, 3, 4] type, which
∗
Presented at the Workshop on Unquenched Hadron Spectroscopy: Non-Perturbative
Models and Methods of QCD vs. Experiment
(1)
The masses and axial currents of the doubly charmed baryons
Zhi-Feng Sun1,2,∗ Zhan-Wei Liu3 ,† Xiang Liu1,2 ,‡ and Shi-Lin Zhu4,5,6§
1
School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
Research Center for Hadron and CSR Physics, Lanzhou University and Institute of Modern Physics of CAS, Lanzhou 730000, China
3
CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia 5005,
Australia 4 School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China
5
Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
6
Center of High Energy Physics, Peking University, Beijing 100871, China
arXiv:1411.2117v1 [hep-ph] 8 Nov 2014
2
The chiral dynamics of the doubly heavy baryons is solely governed by the light quark. In this work, We have
derived the chiral corrections to the mass of the doubly heavy baryons up to N3 LO. The mass splitting of Ξcc and
Ωcc at the N2 LO depends on one unknown low energy constant c7 . With the experimental mass of Ξcc (3520) as
the input, we estimate the mass of Ωcc to be around 3.678 GeV. Moreover, we have also performed a systematical
analysis of the chiral corrections to the axial currents and axial charges of the doubly heavy baryons. The chiral
structure and analytical expressions will be very useful to the chiral extrapolations of the future lattice QCD
simulations of the doubly heavy baryons.
PACS numbers: 14.40.Rt, 14.40.Lb, 12.39.Hg, 12.39.Pn
I.
INTRODUCTION
As one of the most important groups in the baryon family,
the doubly charmed baryons are composed of two charmed
quarks and one light quark (the doubly heavy baryons Ξ++
cc ,
Ξ+cc and Ω+cc with quark components ccu, ccd and ccs, respectively), which were predicted in the quark model (see Ref.
[1] for a detailed review). In the past decades, there have been
some experimental efforts in the search of the doubly charmed
baryons [2–5]. The SELEX Collaboration announced the first
observation of the doubly charmed baryon Ξ+cc (3520) with the
mass M = 3519 ± 1 MeV and width Γ = 3 MeV [2], where
the observed decay mode is Ξ+cc → Λ+c K − π+ . Later, Ξ+cc (3520)
was confirmed by SELEX in the pD+ K − decay channel with
the mass 3518.7 ± 1.7 MeV [4]. Although SELEX also reported Ξ+cc (3520), these results were not confirmed by FOCUS
[6], BaBar [7], Belle [8] and LHCb collaborations [9].
The doubly charmed baryons have been extensively studied with different theoretical approaches. The Ξcc mass was
predicted to be 3.48 ∼ 3.74 GeV in the quark model, while
the Ωcc mass is estimated to be 3.59 ∼ 3.86 GeV [10–22].
The Lattice QCD groups also studied these systems [23–27],
where the predicted mass of Ξcc is 3.51 ∼ 3.67 GeV and the
mass of Ωcc is 3.68 ∼ 3.76 GeV.
The mass splittings of baryons within the same multiplet
encode important information on their inner structure. For example, the mass splittings of the light baryons were reviewed
in Refs. [28, 29]. In Refs. [30, 31], the mass splitting of
the singly heavy baryons was studied within the framework
of the chiral perturbation theory. In Ref. [32], the authors investigated the mass splitting of the doubly heavy baryons by
considering the heavy diquark symmetry. Besides the baryon
∗ Electronic
address: sunzhif09@lzu.edu.cn
address: zhan-wei.liu@adelaide.edu.au
‡
Electronic address: xiangliu@lzu.edu.cn
§ Electronic address: zhusl@pku.edu.cn
† Electronic
mass, the axial current and axial charge of the baryons are
also very important observables, which attract lots of attention [33–55] .
The experimental search of the doubly charmed baryons is
full of challenges and opportunities. In this work, we adopt
the chiral perturbation theory to calculate the chiral corrections to the doubly charmed baryon masses and their mass
splittings, which will be helpful to further experimental exploration of the doubly charmed baryons. Under the same framework, we also study the chiral corrections to the axial charge
and axial current of the doubly charmed baryons, which may
be measured through the semileptonic decays of the doubly
charmed baryons in the future.
Chiral perturbation theory (χPT) is an elegant framework to
deal with the low energy process in hadron physics. With the
help of the chiral power counting scheme proposed by Weinberg et al. [56, 57], one can consider the chiral corrections to
the physical observables order by order.
In the baryon sector, the baryon mass does not vanish in the
chiral limit. This inherent mass scale breaks the naive chiral
power counting. To solve this issue, various schemes were
proposed such as the heavy baryon χPT, infrared baryon χPT,
and extended on-mass-shell method etc.
In the heavy baryon χPT, the baryon is treated to be extremely heavy and acts as a static source [54], which allows
us to take the non-relativistic limit of the fully relativistic theory and make expansion in powers of the inverse baryon mass.
For the case of infrared regularization, the loop integral can be
separated into infrared regular part and infrared singular one
[58, 59], where the later one conserves the Weinberg’s power
counting rule. In the extended on-mass-shell method, the
power counting breaking terms are subtracted and the low energy constants are redefined [60–63]. In our work, we use the
heavy baryon χPT approach to investigate the chiral corrections to the masses and axial currents of the doubly charmed
baryons.
This paper is organized as follows. After the introduction,
we introduce the chiral Lagrangians of the doubly charmed
baryons and its non-relativistic reduction in Sec. II. Then we
arXiv:1411.2097v1 [hep-ph] 8 Nov 2014
The Multiple Point Principle of the Standard Model with
Scalar Singlet Dark Matter and Right Handed Neutrinos
Kiyoharu Kawana∗
Department of Physics, Kyoto University, Kyoto 606-8502, Japan
November 11, 2014
Abstract
We consider the multiple point principle (MPP) of the Standard Model with the scalar
singlet Dark Matter and three heavy right-handed neutrinos. We make two-loop analysis and find that the effective Higgs self coupling λeff can become zero at the scale where
its beta function βλeff becomes zero. The MPP predicts the strong relation between the
top quark mass Mt and the Higgs portal coupling κ, and large Mt (& 171GeV) is allowed. This is a favorable result from the recent experimental value: Mt = 173.34±0.76
GeV.
∗
E-mail: kiyokawa@gauge.scphys.kyoto-u.ac.jp
1
WITS-CTP-137
DESY 14-090
arXiv:1411.2040v1 [hep-ph] 7 Nov 2014
Confronting Higgs couplings from D-term extensions
and Natural SUSY at the LHC and ILC
Moritz McGarrie,F,♠ Gudrid Moortgat-Pick♣,♦ and Stefano Porto♣
F
School of Physics and Centre for Theoretical Physics, University of the Witwatersrand,
Johannesburg, WITS 2050, South Africa
♠
Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,
ul. Ho˙za 69, 00-681 Warszawa, Poland
♣
II. Institut f¨
ur Theoretische Physik, Universit¨
at Hamburg,
Luruper Chaussee 149, 22761 Hamburg, Germany
♦
DESY, Deutsches Elektronen-Synchrotron,
Notkestraße 85, D-22607 Hamburg, Germany
Abstract: Non-decoupling D-term extensions of the MSSM enhance the tree-level Higgs
mass compared to the MSSM, therefore relax fine-tuning and may allow lighter stops with
rather low masses even without maximal mixing. We present the anatomy of various nondecoupling D-term extensions of the MSSM and explore the potential of the LHC and of
the International Linear Collider (ILC) to determine their deviations in the Higgs couplings
with respect to the Standard Model. Depending on the mass of the heavier Higgs mH ,
such deviations may be constrained at the LHC and determined at the ILC. We evaluate
the Higgs couplings in different models and study the prospects for a model distinction at
√
the different stages of the ILC at s =250, 500, 1000 GeV, including the full luminosity
upgrade and compare it with the prospects at HL-LHC.
IPPP/14/96
DCTP/14/192
The Dimension Six Triple Gluon Operator
in Higgs+Jet Observables
arXiv:1411.2029v1 [hep-ph] 7 Nov 2014
Diptimoy Ghosha∗
a
b
Martin Wiebuschb†
INFN, Sezione di Roma, Piazzale A. Moro 2, I-00185 Roma, Italy
Institute for Particle Physics Phenomenology, Department of Physics, Durham
University, Durham CH1 3LE, United Kingdom
Abstract
Recently a lot of progress has been made towards a full classification of new
physics effects in Higgs observables by means of effective dimension six operators.
Specifically, Higgs production in association with a high transverse momentum
jet has been suggested as a way to discriminate between operators that modify the Higgs-top coupling and operators that induce an effective Higgs-gluon
coupling—a distinction that is hard to achieve with signal strength measurements
alone. With this article we would like to draw attention to another source of
new physics in Higgs+jet observables: the triple gluon operator O3g (consisting
of three factors of the gluon field strength tensor). We compute the distortions
of kinematic distributions in Higgs+jet production at a 14 TeV LHC due to O3g
and compare them with the distortions due to dimension six operators involving
the Higgs doublet. We find that the transverse momentum, the jet rapidity and
the difference between the Higgs and jet rapidity are well suited to distinguish
between the contributions from O3g and those from other operators, and that the
size of the distortions are similar if the Wilson coefficients are of the same order as
the expected bounds from other observables. We conclude that a full analysis of
new physics in Higgs+jet observables must take the contributions from O3g into
account.
∗
†
email: diptimoy.ghosh@roma1.infn.it
email: martin.wiebusch@durham.ac.uk
arXiv:1411.2353v1 [nucl-th] 10 Nov 2014
136
Sn and three body forces
M. Saha Sarkar ∗, S. Sarkar †
Saha Institute of Nuclear Physics, Bidhannagar, Kolkata-700064, INDIA
Indian Institute of Engineering Science and Technology, Shibpur, Howrah - 711103, INDIA
November 11, 2014
Abstract
+
New experimental data on 2 energies of 136,138 Sn confirms the trend of lower 2+ excitation
energies of even-even tin isotopes with N > 82 compared to those with N< 82. However,
none of the theoretical predictions using both realistic and empirical interactions can reproduce
experimental data on excitation energies as well as the transition probabilities (B(E2; 6+ →
4+ )) of these nuclei, simultaneously, apart from one whose matrix elements have been changed
empirically to produce mixed seniority states by weakening pairing. We have shown that the
experimental result also shows good agreement with the theory in which three body forces have
been included in a realistic interaction. The new theoretical results on transition probabilities
have been discussed to identify the experimental quantities which will clearly distinguish between
different views.
1
Introduction
Nuclei around doubly closed 132 Sn lie on or close to the path of astrophysical r-process flow. Structure of these nuclei, particularly the binding energy (BE), low-lying excited states and beta decay
rates at finite temperatures are important ingredients for nucleosynthesis calculation. However,
these nuclei are usually experimentally inaccessible by common techniques of nuclear spectroscopy.
So far experimental investigations have been performed using spontaneous fission sources, thermal
- neutron - induced fission deep inelastic reactions, fragmentation and fission at intermediate and
relativistic energies. Reactions with neutron rich radioactive ion beams are expected to generate
very important, reliable data base for these nuclei.
So far the experimental status [1] was not at all satisfactory for Sn isotopes beyond 132 Sn. Spectroscopic information, such as BE and low lying spectrum, is known experimentally only for 134 Sn.
Half-lives of 135−137 Sn have been measured through β-n decay process. Lifetimes of these nuclei
are very small and production rates are also very low presenting challenges to spectroscopic studies.
Reliable theoretical results are therefore necessary and useful, especially as inputs to calculations
for astrophysical processes. Being close to the doubly closed neutron-rich 132 Sn nucleus, this region
therefore has been taken as a fertile ground for testing nuclear shell model (SM) with interactions
suited for nuclei far from stability.
∗ maitrayee.sahasarkar@saha.ac.in
† ss@physics.becs.ac.in
1
Results on Heavy-Flavour Production in pp, p–
Pb and Pb–Pb Collisions with ALICE at the LHC
Grazia Luparello1 for the ALICE Collaboration
arXiv:1411.2442v1 [nucl-ex] 10 Nov 2014
1
Universit`
a di Trieste and INFN - Trieste, via A. Valerio 2, Trieste, Italy
DOI: will be assigned
The ALICE Collaboration has measured heavy-flavour production through the reconstruction of hadronic decays of D mesons at mid-rapidity and via semi-electronic (at midrapidity) and semi-muonic (at forward rapidity) decays of charm and beauty hadrons in
pp, p–Pb and Pb–Pb collisions. A summary of the most recent results from p–Pb collisions
√
√
at sN N = 5.02 TeV and Pb–Pb collisions at sN N = 2.76 TeV is presented in this paper.
1
Introduction
Heavy quarks are effective probes of the Quark Gluon Plasma (QGP) formed in high-energy
nucleus-nucleus collisions, since they are produced on a short time scale with respect to that of
the QGP. They traverse the strongly interacting medium and lose energy through radiative [1]
and collisional [2] processes. Theoretical calculations predict a dependence of the energy loss
on the colour charge and on the mass of the parton traversing the medium, resulting in a
hierarchy in the energy loss with beauty quarks losing less energy than charm quarks, and charm
quarks losing less energy than light quarks and gluons [3, 4]. The energy loss is experimentally
investigated via the nuclear modification factor RAA , defined as the ratio of the yield in nucleusnucleus collisions to that observed in pp collisions scaled by the number of binary nucleonnucleon collisions. In the absence of medium effects, RAA is expected to be unity for heavy
flavours, since the production yields are proportional to the number of binary nucleon-nucleon
collisions. The expected hierarchy in the energy loss described above can be verified comparing
the RAA of different particle species, namely RAA (B) > RAA (D) > RAA (light). For this
comparison it should be considered that the RAA of the different hadronic species are also
affected by the different production kinematics and fragmentation function of gluons, light and
heavy quarks. The RAA can be modified also due to initial-state effects, since the nuclear
environment affects the quark and gluon distributions as described either by calculations based
on phenomenological modifications of the Parton Distribution Functions (PDF) [5] or by the
Colour Glass Condensate (CGC) effective theory [6]. Partons can also lose energy in the initial
stages of the collision via initial-state radiation [7], or they can experience transverse momentum
broadening due to multiple soft collisions prior to the hard scattering [8]. Initial-state effects are
addressed by studying p–Pb collisions. Finally, in nucleus-nucleus collisions the charmed hadron
azimuthal anisotropy, quantified via the second order coefficient of the Fourier decomposition of
the particle momentum azimuthal distribution (v2 ), tests whether also charm quarks participate
in the collective expansion dynamics and possibly thermalize in the QGP.
PANIC14
1
SNSN-XXX-YY
November 11, 2014
arXiv:1411.2396v1 [nucl-ex] 10 Nov 2014
Recent results from the search for the critical point of strongly
interacting matter at the CERN SPS
Grzegorz Stefanek1
for the NA49 and NA61/SHINE Collaborations
Institute of Physics
Jan Kochanowski University, Swietokrzyska 15, 25-406 Kielce, POLAND
Recent searches at the CERN SPS for evidence of the critical point of
strongly interacting matter are discussed. Experimental results on theoretically expected signatures, such as event-to-event fluctuations of the
particle multiplicity and the average transverse momentum as well as intermittency in particle production are presented.
PRESENTED AT
XXXIV Physics in Collision Symposium
Bloomington, Indiana, September 16–20, 2014
1
Work supported by the Polish National Science Centre under contracts on the basis of decisions
no. DEC-2011/03/B/ST2/02617, DEC-2012/04/M/ST2/00816
1
Introduction
The exploration of the phase diagram of strongly interacting matter, particularly
the search for a phase transition from hadronic to partonic degrees of freedom and
possibly a critical endpoint, is one of the most challenging tasks in present heavy ion
physics.
NA49 data on inclusive hadron production indicate that the onset of deconfine√
ment in central Pb+Pb collisions is located at 30A GeV beam energy( sN N =7.7 GeV).
It is mainly based on the observation of norrow structures in the energy dependence of
hadron production in central Pb+Pb collisions which are not observed in elementary
interactions [1, 2]. The NA61/SHINE experiment [3] continues the ion program of
NA49 with the main aim of searching for the critical point and studying in detail the
onset of deconfinement by performing a two dimensional scan of the phase diagram in
T and µB . This is achieved by varying collision energy (13A-158A GeV) and size of
the colliding systems. The data sets recorded by both experiments and those planned
to be recorded by NA61/SHINE for the scan of the phase diagram are presented in
Fig. 1. Chemical freeze-out points in Fig. 1(right) are taken from [4]. The presence
of the predicted critical point is expected to lead to an increase of event-by-event
fluctuations of many observables [5, 6] provided that the freeze-out of the measured
hadrons occurs close to its location in the phase diagram and the evolution of the final
hadron phase does not erase the fluctuation signals. The NA61/SHINE experiment
looks for a maximum of fluctuations as experimental signature for the critical point.
Figure 1: Left: Data sets collected (green) and planned to be recorded by
NA61/SHINE within (light blue) and beyond (yellow) the approved ion program.
Right: The planned scan of the phase diagram by varying collision energy (µB )
and size of colliding nuclei (T ). Chemical freeze-out points are taken from [4] and
parametrizations therein.
1
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