Nuclear Theory·nucl-th

Tuesday·April 18, 2017

26 papers—15 primary·11 cross-listed

01
[Submitted on 15 Apr 2017]
Neutrino-nucleus cross-sections at supernova neutrino energies
S. Chauhan🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳
The inclusive neutrino/antineutrino-induced charged and neutral current reaction cross-sections in $^{12} C$ , $^{16} O$ , $^{40} A r$ , $^{56} F e$ and $^{208} P b$ in the energy region of supernova neutrinos/antineutrinos are studied. The calculations are performed in the local density approximation (LDA) taking into account the effects due to Pauli blocking, Fermi motion and the renormalization of weak transition strengths in the nuclear medium. The effect of Coulomb distortion of the lepton produced in the charged current reactions has also been included. The numerical results for the energy dependence of the cross-section $σ (E)$ as well as the flux averaged cross-section and event rates for the charged lepton production in the case of some supernova neutrino/antineutrino fluxes recently discussed in the literature have been presented. We have also given the flux-averaged angular and energy distributions of the charged leptons corresponding to these fluxes.
Comments:
23 pages, 11 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.04582 [pdf]
IJMPE(2017)·9 citations
02
[Submitted on 15 Apr 2017]
Revealing the collision energy dependence of $η / s$ in RHIC-BES Au+Au collisions using Bayesian statistics
Jussi Auvinen🇺🇸 · Iurii Karpenko🇮🇹 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸
We investigate the collision energy dependence of $η / s$ in a transport + viscous hydrodynamics hybrid model. A Bayesian analysis is performed on RHIC beam energy scan data for $A u + A u$ collisions at $s_{N N} = 19.6, 39,$ and $62.4$ GeV. The resulting posterior probability distributions for the model parameters show a preference for a larger value of $η / s$ at $19.6$ GeV compared to $62.4$ GeV, indicating dependence on baryon chemical potential $μ_{B}$ .
Comments:
7 pages, 3 figures. Talk by J. Auvinen at Quark Matter 2017, February 6-11, 2017, Chicago, IL, USA
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1704.04643 [pdf]
NPA(2017)·10 citations
03
[Submitted on 15 Apr 2017]
Event-by-event $v_{n}$ correlations of soft hadrons and heavy mesons in heavy ion collisions
Caio A. G. Prado🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Roland Katz🇧🇷 · Jorge Noronha🇧🇷 · Marcelo G. Munhoz🇧🇷 · Alexandre A. P. Suaide🇧🇷
Combining event-by-event hydrodynamics with heavy quark energy loss we compute correlations between the heavy and soft sectors for elliptic and triangular flow harmonics $v_{2}$ and $v_{3}$ of D $^{0}$ mesons in PbPb collisions at $2.76$ TeV and $5.02$ TeV. Our results indicate that $v_{3}$ is strongly influenced by the fragmentation temperature and that it builds up later than $v_{2}$ during the evolution of the system.
Comments:
4 pages, 3 figures, contribution to the proceedings of Quark Matter - XXVI international conference on ultrarelativistic heavy-ion collisions (Chicago, USA, February 5 to February 11, 2017) - Version2: accepted for publication
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1704.04654 [pdf]
NPA(2017)·2 citations
04
[Submitted on 15 Apr 2017]
Bulk viscous effects on flow and dilepton radiation in a hybrid approach
Gojko Vujanovic🇺🇸 · Jean-François Paquet🇺🇸 · Sangwook Ryu🇩🇪 · Chun Shen🇺🇸 · Gabriel S. Denicol🇧🇷 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦 · Ulrich Heinz🇺🇸
Starting from IP-Glasma initial conditions, we investigate the effects of bulk pressure on low mass dilepton production at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) energies. Though thermal dilepton $v_{2}$ is affected by the presence of both bulk and shear viscosity, whether or not these effects can be measured depends on the dilepton "cocktail" contribution to the the low mass dilepton $v_{2}$ . Combining the thermal and "cocktail" dileptons, the effects of bulk viscosity on total dilepton $v_{2}$ is investigated.
Comments:
Proceedings for the 26th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017), February 5-11 2017, Chicago, Illinois, USA
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1704.04687 [pdf]
NPA(2017)·6 citations
05
[Submitted on 16 Apr 2017]
Viscous anisotropic hydrodynamics for the Gubser flow
M. Martinez · M. McNelis · U. Heinz
In this work we describe the dynamics of a highly anisotropic system undergoing boost-invariant longitudinal and azimuthally symmetric radial expansion (Gubser flow) for arbitrary shear viscosity to entropy density ratio. We derive the equations of motion of dissipative anisotropic hydrodynamics by applying to this situation the moments method recently derived by Molnár et al. (MNR) [1,2], based on an expansion around an arbitrary anisotropic one-particle distribution function. One requires an additional evolution equation in order to close the conservation laws. This is achieved by selecting the relaxation equation for the longitudinal pressure with a suitable Landau matching condition. As a result one obtains two coupled differential equations for the energy density and the longitudinal pressure which respect the $S O (3)_{q} \otimes S O (1, 1) \otimes Z_{2}$ symmetry of the Gubser flow in the deSitter space. These equations are solved numerically and compared with the predictions of the recently found exact solution of the relaxation-time-approximation Boltzmann equation subject to the same flow. We also compare our numerical results with other fluid dynamical models. We observe that the MNR description of anisotropic fluid dynamics reproduces the space-time evolution of the system than all other currently known hydrodynamical approaches.
Comments:
4 pages, 1 Figure. Proceedings of the XXVIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017) Chicago, February 6-11, 2017
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.04727 [pdf]
NPA(2017)·1 citation
06
[Submitted on 16 Apr 2017]
Test the accuracy of the Dubna phenomenological model of the masses of the atomic nuclei
Strachimir Cht. Mavrodiev
In this paper is presented the reliability test the numerical generalization of Bethe-Weizsacker mass formula which describes the values of measured 2654 nuclei masses in AME2012 nuclear database: https://www-nds.iaea.org/amdc/, with accuracy in the interval (-1.90,1.80) MeV, for the nulear with mass number A=2(1,1) to 294(117,177). In the analyzed generalization of the Bethe-Weizsacker formula the little correction of proton and neutron magic numbers and boundaries of their influence was derived as a solution of nonlinear inverce problem (Ivanenko shell model!). There was confirmed the existence of ten proton (2,8,14,20,28,50,82,96,108,126) and eleven neutron (2,8,14,20,28,50,82,126,142,152,184) magic numbers. The test was performed analyzing the new data from Nuclide ground states: https://www-nds.iaea.org/relnsd/NdsEnsdf/QueryForm.html, containing 3182 data for A=2(1,1) to 294(118,176) and confirmed the above values of proton and neutron magic numbers. The accuracy of masses description is in the interval (-2.80,1.80) MeV. Only fourteen nuclear masses have bigger than 1.90 MeV residual.
Comments:
86 pages, 5 fihures, 3 tables. arXiv admin note: substantial text overlap with arXiv:1607.07217
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.04748 [pdf]
0 citations
07
[Submitted on 16 Apr 2017]
Dynamical fluctuations in critical regime and across the 1st order phase transition
Lijia Jiang · Shanjin Wu · Huichao Song
In this proceeding, we study the dynamical evolution of the sigma field within the framework of Langevin dynamics. We find that, as the system evolves in the critical regime, the magnitudes and signs of the cumulants of sigma field, $C_{3}$ and $C_{4}$ , can be dramatically different from the equilibrated ones due to the memory effects near $T_{c}$ . For the dynamical evolution across the 1st order phase transition boundary, the supercooling effect leads the sigma field to be widely distributed in the thermodynamical potential, which largely enhances the cumulants $C_{3}, C_{4}$ , correspondingly.
Comments:
4 pages, 2 figures, proceedings for Quark Matter 2017
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.04765 [pdf]
NPA(2017)·21 citations
08
[Submitted on 16 Apr 2017]
Structure of $^{14}$ C and $^{14}$ O nuclei calculated in the variational approach
B. E. Grinyuk · D. V. Piatnytskyi
The structure of mirror $^{14}$ C and $^{14}$ O nuclei has been studied in the framework of the five-particle model (three $α$ -particles and two nucleons). Interaction potentials are proposed, which allowed the energy and radius of $^{14}$ C nucleus, as well as the energy of $^{14}$ O one, to agree with experimental data. On the basis of the variational approach with the use of Gaussian bases, the energies and wave functions for five-particle systems under consideration are calculated. The charge radius of $^{14}$ O nucleus, as well as the charge density distributions and the form factors for both nuclei, are predicted.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.04824 [pdf]
Ukr.J.Phys.(2016)·3 citations
09
[Submitted on 17 Apr 2017]
Properties and uses of factorial cumulants in relativistic heavy-ion collisions
Masakiyo Kitazawa🇯🇵 · Xiaofeng Luo🇺🇸
We discuss properties and applications of factorial cumulants of various particle numbers and for their mixed channels measured by the event-by-event analysis in relativistic heavy-ion collisions. After defining the factorial cumulants for systems with multi-particle species, their properties are elucidated. The uses of the factorial cumulants in the study of critical fluctuations are discussed. We point out that factorial cumulants play useful roles in understanding fluctuation observables when they have underlying physics approximately described by the binomial distribution. As examples, we suggest novel utilization methods of the factorial cumulants in the study of the momentum cut and rapidity window dependences of fluctuation observables.
Comments:
17 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1704.04909 [pdf]
PRC(2017)·50 citations
10
[Submitted on 17 Apr 2017]
Chemical freeze-out in relativistic heavy-ion collisions
Jun Xu🇨🇳 · Che Ming Ko🇺🇸
One surprising result in relativistic heavy-ion collisions is that the abundance of various particles measured in experiments is consistent with the picture that they reach chemical equilibrium at a temperature much higher than the temperature they freeze out kinetically. Using a multiphase transport model to study particle production in these collisions, we find that the above result is due to the constancy of the entropy per particle during the evolution of the hadronic matter from the chemical to the kinetic freeze-out. We further use a hadron resonance gas model to illustrate the result from the transport model study.
Comments:
5 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
1704.04934 [pdf]
PLB(2017)·37 citations
11
[Submitted on 17 Apr 2017]
The onset of fluid-dynamical behavior in relativistic kinetic theory
Jorge Noronha (Sao Paulo U.)🇧🇷 · Gabriel S. Denicol (Niteroi, Fluminense U.)🇧🇷
In this proceedings we discuss recent findings regarding the large order behavior of the Chapman-Enskog expansion in relativistic kinetic theory. It is shown that this series in powers of the Knudsen number has zero radius of convergence in the case of a Bjorken expanding fluid described by the Boltzmann equation in the relaxation time approximation. This divergence stems from the presence of non-hydrodynamic modes, which give non-perturbative contributions to the Knudsen series.
Comments:
4 pages, 1 figure, proceedings for Quark Matter 2017
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1704.04976 [pdf]
NPA(2017)·2 citations
12
[Submitted on 17 Apr 2017]
Mixed Harmonic Correlations: Hydrodynamics Predictions at RHIC using Experimental Analysis Techniques
Fernando G. Gardim🇧🇷 · Frederique Grassi🇧🇷 · Matthew Luzum🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸
Correlations of different azimuthal flow harmonics $v_{n}$ and symmetry planes $Ψ_{n}$ can add constraints to theoretical models, and probe aspects of the system that are independent of the traditional single-harmonic measurements. Using NeXSPheRIO, a hydrodynamical model which has accurately reproduced a large set of single-harmonic correlations at RHIC, we make predictions of these new observables for 200 A GeV Au+Au Collisions, providing an important baseline for comparison to correlations of flow harmonics, which contain non-trivial information about the initial state. We also point out how to properly compare theoretical calculations to measurements using wide centrality bins and non-trivial event weighting.
Comments:
5 pages, 5 figures, Proceedings of the XXVI International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1704.04983 [pdf]
NPA(2017)·0 citations
13
[Submitted on 14 Apr 2017]
Phenomenology of the muon-induced neutron yield
Alexey Malgin🇷🇺
The cosmogenic neutron yield $Y_{n}$ characterizes the matter ability to produce neutrons under the effect of cosmic ray muons with spectrum and average energy corresponding to an observation depth. The yield is the basic characteristic of cosmogenic neutrons. The neutron production rate and neutron flux both are derivatives of the yield. The constancy of the exponents $α$ and $β$ in the known dependences of the yield on energy $Y_{n} \propto E_{μ}^{α}$ and the atomic weight $Y_{n} \propto A^{β}$ allows to combine these dependences in a single formula and to connect the yield with muon energy loss in the matter. As a result, the phenomenological formulas for the yield of muon-induced charged pions and neutrons can be obtained. These expressions both are associated with nuclear loss of the ultrarelativistic muons, which provides the main contribution to the total neutron yield. The total yield can be described by a universal formula, which is the best fit of experimental data.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1704.04993 [pdf]
PRC(2017)·14 citations
14
[Submitted on 17 Apr 2017]
Optimized fluid dynamics for heavy ion collisions
Dennis Bazow · Ulrich W. Heinz · Michael Strickland
The (viscous) anisotropic hydrodynamic approach, especially after perturbative inclusion of all residual viscous terms, has been shown to dramatically outperform viscous hydrodynamics in several simplified situations for which exact solutions exist but which share with realistic expansion scenarios the problem of large dissipative currents. We will report on the present status of applying viscous anisotropic hydrodynamics in a highly efficient simulation of the full three-dimensional quark-gluon plasma. Results from accelerated $3 + 1$ -dimensional viscous hydrodynamic simulations using graphics processing units will be compared to the anisotropic frameworks.
Comments:
4 pages, 1 figure. Talk presented at Quark Matter 2017, 5-11 February 2017, Chicago, USA
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.04996 [pdf]
NPA(2017)·0 citations
15
[Submitted on 17 Apr 2017]
Constructing realistic alpha cluster channels
Konstantinos Kravvaris · Alexander Volya
We present techniques that allow for $α$ -cluster channels with realistic $α$ -particle wave functions from No Core Shell Model calculations to be constructed. We compare results of several clustering calculations with realistic $α$ wave functions to those assuming a trivial $(0 s)^{4}$ structure.
Comments:
3 pages, 1 table, 11th International Conference on Clustering Aspects of Nuclear Structure and Dynamics
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1704.05010 [pdf]
J.Phys.Conf.Ser.(2017)·6 citations
16
[Submitted on 14 Apr 2017] (cross-list from hep-ph)
Effective Field Theory Models for Thermal QCD
Sourendu Gupta🇮🇳 · Rishi Sharma🇮🇳
We present an effective field theory model for QCD at finite temperature with quarks. We discuss the mean field theory, the fixing of parameters, and a prediction for the curvature of the critical line. We proceed to write down a pionic theory of fluctuations around the mean field, and discuss how the parameters of this pionic effective theory descend from the model with quarks.
Comments:
Proceedings of Quark Matter 2017
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1704.04495 [pdf]
NPA(2017)·1 citation
17
[Submitted on 14 Apr 2017] (cross-list from hep-ph)
Structure of virtual photon polarization in ultrarelativistic heavy-ion collisions
Gordon Baym🇺🇸 · Tetsuo Hatsuda🇯🇵 · Michael Strickland🇺🇸
Anisotropy in heavy-ion collisions leads to polarization of both direct and virtual photons, the latter detected via internal conversion to dileptons pairs. Thus measurement of photon polarization probes the anisotropy at all stages of collisions. In order to characterize the polarization of virtual photons, we derive here the general structure of the photon polarization operator, rho^(mu nu), in an anisotropic medium, in terms of the four spectral functions, two transverse and one longitudinal, as usual, plus a new spectral function that reflects anisotropy in asymmetric collisions; and derive the local production rate of dilepton pairs in terms of these four functions.
Comments:
4 pages, 4 figures; proceedings contribution for Quark Matter 2017
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.04526 [pdf]
NPA(2017)·5 citations
18
[Submitted on 15 Apr 2017] (cross-list from nucl-ex)
PHENIX Overview
D. McGlinchey (for the PHENIX Collaboration)🇺🇸
These proceedings present highlighted results from PHENIX shown at the Quark Matter 2017 conference.
Comments:
XXVIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017)
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1704.04568 [pdf]
NPA(2017)·3 citations
19
[Submitted on 15 Apr 2017] (cross-list from hep-ph)
A Unified Description for Comprehensive Sets of Jet Energy Loss Observables with CUJET3
Shuzhe Shi🇺🇸 · Jiechen Xu🇺🇸 · Jinfeng Liao🇺🇸 · Miklos Gyulassy🇺🇸
Jet energy loss in heavy ion collisions, as quantified by the traditional observable of high $p_{T}$ hadron's nuclear modification factor $R_{AA}$ , provides highly informative "imaging" of the hot medium created in heavy ion collisions. There are now comprehensive sets of available data, from average suppression to azimuthal anisotropy, from light to heavy flavors, from RHIC 200GeV to LHC 2.76TeV as well as 5.02TeV collisions. A unified description of such comprehensive data presents a stringent vetting of any viable model for jet quenching phenomenology. In this contribution we report such a systematic and successful test of CUJET3, a jet energy loss simulation framework built upon a nonperturbative microscopic model for the hot medium as a semi-quark-gluon-monopole plasma (sQGMP) which integrates two essential elements of confinement, i.e. the Polyakov-loop suppression of quarks/gluons and emergent magnetic monopoles.
Comments:
4 pages, 3 figures, contribution to the Proceedings of XXVIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1704.04577 [pdf]
NPA(2017)·9 citations
20
[Submitted on 15 Apr 2017] (cross-list from hep-ph)
Spontaneous Spin Polarization due to Tensor Selfenergies in Quark Matter
Tomoyuki Maruyama🇯🇵 · Toshitaka Tatsumi🇯🇵
We study the magnetic properties of quark matter in the NJL model with the tensor interaction. The spin-polarized phase given by the tensor interaction remains even when the quark mass is zero, while the phase given by the axial vector interaction disappears. There are two kinds of spin-polarized phases: one appears in the chiral-broken phase, and the other appears in the chiral-restored phase where the quark mass is zero. The latter phase can appear independently of the strength of the tensor interaction.
Comments:
24 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.04596 [pdf]
PRD(2017)·9 citations
21
[Submitted on 16 Apr 2017] (cross-list from hep-th)
Exact Self-Dual Skyrmions
L.A. Ferreira🇧🇷 · Ya. Shnir🇷🇺
We introduce a Skyrme type model with the target space being the 3-sphere S^3 and with an action possessing, as usual, quadratic and quartic terms in field derivatives. The novel character of the model is that the strength of the couplings of those two terms are allowed to depend upon the space-time coordinates. The model should therefore be interpreted as an effective theory, such that those couplings correspond in fact to low energy expectation values of fields belonging to a more fundamental theory at high energies. The theory possesses a self-dual sector that saturates the Bogomolny bound leading to an energy depending linearly on the topological charge. The self-duality equations are conformally invariant in three space dimensions leading to a toroidal ansatz and exact self-dual Skyrmion solutions. Those solutions are labelled by two integers and, despite their toroidal character, the energy density is spherically symmetric when those integers are equal and oblate or prolate otherwise.
Comments:
14 pages, 3 figures, a reference added
Subjects:
High Energy Physics — Theory (hep-th); Mathematical Physics (math-ph); math.MP (math.MP); nlin.SI (nlin.SI); Nuclear Theory (nucl-th)
arXiv:
1704.04807 [pdf]
PLB(2017)·21 citations
22
[Submitted on 16 Apr 2017] (cross-list from nucl-ex)
Jet Measurements with Neutral and Di-jet Triggers in Central Au+Au Collisions at $s_{N N}$ = 200 GeV with STAR
Nihar Ranjan Sahoo (for the STAR Collaboration)🇺🇸
We present two measurements related to jet production in p+p and central Au+Au collisions at $s_{N N}$ =200 GeV. Firstly, a study of semi-inclusive charged recoil jets coincident with high- $p_{T}$ direct-photon and neutral pions, and secondly, the hadron correlations with respect to reconstructed di-jet triggers. Indication of medium effects is observed by comparing $γ$ +jet and $π^{0}$ +jet measurements. The di-jet+hadron study shows signs that the medium-induced modifications of an imbalanced set of di-jets with "hard cores" primarily affect the recoil jet.
Comments:
4 pages, 3 Figures, proceedings for the Quark Matter 2017
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.04814 [pdf]
NPA(2017)·1 citation
23
[Submitted on 17 Apr 2017] (cross-list from hep-ph)
In-Medium Bottomonium Production in Heavy-Ion Collisions
Xiaojian Du🇺🇸 · Min He🇨🇳 · Ralf Rapp🇺🇸
We study bottomonium production in heavy-ion collisions using a transport model which utilizes kinetic-rate and Boltzmann equations to calculate the energy, centrality and transverse-momentum ( $p_{T}$ ) dependence of the yields. Both gluo-dissociation and inelastic parton-induced break-up including interference effects are improved over previous work by using in-medium binding energies from a thermodynamic $T$ -matrix approach. A coalescence model with bottom-quark spectra from Langevin simulations is implemented to account for thermal off-equilibrium effects in the $p_{T}$ -spectra of the regeneration contribution. We also update the equation of state for the bulk medium by extracting it from lattice-QCD results. A systematic analysis of bottomonium observables is conducted in comparison to RHIC and LHC data. In particular, the off-equilibrium bottom-quark spectra are found to play an important role in the bottomonium $p_{T}$ spectra.
Comments:
4 pages, 6 figures; Proceeding on XXVIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2017) (Chicago, IL, USA), February 6-11, 2017
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.04838 [pdf]
NPA(2017)·10 citations
24
[Submitted on 17 Apr 2017] (cross-list from hep-ph)
Charmed Baryon $Λ_{c}$ in Nuclear Matter
Keisuke Ohtani🇯🇵 · Ken-ji Araki🇯🇵 · Makoto Oka🇯🇵
Density dependences of the mass and self-energies of $Λ_{c}$ in nulear matter are studied in the parity projected QCD sum rule. Effects of nuclear matter are taken into account through the quark and gluon condensates. It is found that the four-quark condensates give dominant contributions. As the density dependences of the four-quark condensates are not known well, we examine two hypotheses. One is based on the factorization hypothesis (F-type) and the other is derived from the perturbative chiral quark model (QM-type). The F-type strongly depends on density, while the QM-type gives a weaker dependence. It is found that, for the F-type dependence, the energy of $Λ_{c}$ increases as the density of nuclear matter grows, that is, $Λ_{c}$ feels repulsion. On the other hand, the QM-type predicts a weak attraction ( $\sim 20$ MeV at the normal nuclear density) for $Λ_{c}$ in nuclear matter. We carry out a similar analysis of the $Λ$ hyperon and find that the F-type density dependence is too strong to explain the observed binding energy of $Λ$ in nuclei. Thus we conclude that the weak density dependence of the four-quark condensate is more realistic. The scalar and vector self-energies of $Λ_{c}$ for the QM-type dependence are found to be much smaller than those of the light baryons.
Comments:
14 pages, 6 figures, 2 tables, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1704.04902 [pdf]
PRC(2017)·12 citations
25
[Submitted on 17 Apr 2017] (cross-list from hep-lat)
Topology in the SU(N_f) chiral symmetry restored phase of unquenched QCD and axion cosmology II
Vicente Azcoiti🇪🇸
We investigate the physical consequences of the survival of the effects of the U(1)_A anomaly in the chiral symmetric phase of QCD, and show that the free energy density is a singular function of the quark mass m, in the chiral limit, and that the $σ$ and $π ˉ$ susceptibilities diverge in this limit at any $T \geq T_{c}$ . We also show that the difference between the $π ˉ$ and $δ ˉ$ susceptibilities diverges in the chiral limit at any $T \geq T_{c}$ , a result which seems to be excluded by recent results of Tomiya et al. from numerical simulations of two-flavor QCD. We also discuss on the generalization of these results to the $N_{f} \geq 3$ model.
Comments:
9 pages, no figures, new references added
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1704.04906 [pdf]
PRD(2017)·11 citations
26
[Submitted on 17 Apr 2017] (cross-list from hep-ph)
Patterns and partners for chiral symmetry restoration
A. Gomez Nicola🇪🇸 · J. Ruiz de Elvira🇩🇪
We present and analyze a new set of Ward Identities which shed light on the distinction between different patterns of chiral symmetry restoration in QCD, namely $O (4)$ vs $O (4) \times U (1)_{A}$ . The degeneracy of chiral partners for all scalar and pseudoscalar meson nonet members are studied through their corresponding correlators. Around chiral symmetry degeneration of $O (4)$ partners, our analysis predicts that $U (1)_{A}$ partners are also degenerated. Our analysis also leads to $I = 1/2$ scalar-pseudoscalar partner degeneration at exact chiral restoration, and supports ideal mixing between the $η$ - $η^{'}$ and the $f_{0} (500)$ - $f_{0} (980)$ mesons at $O (4) \times U (1)_{A}$ restoration, with a possible range where the pseudoscalar mixing vanishes if the two transitions are well separated. We test our results with lattice data and provide further relevant observables regarding chiral and $U (1)_{A}$ restoration for future lattice and model analyses.
Comments:
12 pages and 4 figures. Minor clarifications added. Version accepted in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1704.05036 [pdf]
PRD(2018)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE