Nuclear Theory·nucl-th

Tuesday·June 30, 2020

21 papers—12 primary·9 cross-listed

13
[Submitted on 27 Jun 2020] (cross-list from hep-ph)
Excitation Functions of Tsallis-like Parameters in High-Energy Nucleus-Nucleus Collisions
Li-Li Li🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
The transverse momentum spectra of charged pions, kaons, and protons produced at mid-rapidity in central nucleus-nucleus (AA) collisions at high energies are analyzed by considering particles to be created from two participant partons which are assumed to be contributors from the collision system. Each participant (contributor) parton is assumed to contribute to the transverse momentum by a Tsallis-like function. The contributions of the two participant partons are regarded as the two components of transverse momentum of the identified particle. The experimental data measured in high-energy AA collisions by international collaborations are studied. The excitation functions of kinetic freeze-out temperature and transverse flow velocity are extracted. The two parameters increase quickly from $\approx 3$ to $\approx 10$ GeV (exactly from 2.7 to 7.7 GeV) and then slowly at above 10 GeV with the increase of collision energy. In particular, there is a plateau from near 10 GeV to 200 GeV in the excitation function of kinetic freeze-out temperature.
Comments:
22 pages, 7 figures. Special Issue "Hydrodynamics and Thermodynamics in High Energy Physics" in Entropy, accepted
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2006.15333 [pdf]
Entropy(2021)·31 citations
14
[Submitted on 27 Jun 2020] (cross-list from hep-ph)
A Dyson-Schwinger model beyond isospin limit prepared for investigating U_A(1)-breaking temperature dependence
Davor Horvatić🇭🇷 · Dalibor Kekez🇭🇷 · Dubravko Klabučar🇭🇷
Motivated by our earlier findings of sensitive quark-flavor dependence of QCD topological susceptibility on products of current quark masses and corresponding condensates, we allow the breaking of isospin symmetry. For the purpose of future investigations of U_A(1) symmetry breaking and restoration at T > 0, we perform (at T = 0) refitting of the quark-mass parameters of a phenomenologically successful effective model of low-energy QCD. It belongs to the class of separable-interaction models within the Dyson-Schwinger approach to the quark-antiquark substructure of mesons.
Comments:
8 pages, 1 figure, 3 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2006.15395 [pdf]
Eur.Phys.J.ST(2020)·3 citations
15
[Submitted on 27 Jun 2020] (cross-list from hep-ph)
FeynOnium: Using FeynCalc for automatic calculations in Nonrelativistic Effective Field Theories
Nora Brambilla🇩🇪 · Hee Sok Chung🇩🇪 · Vladyslav Shtabovenko🇩🇪 · Antonio Vairo🇩🇪
We present new results on FeynOnium, an ongoing project to develop a general purpose software toolkit for semi-automatic symbolic calculations in nonrelativistic Effective Field Theories (EFTs). Building upon FeynCalc, an existing Mathematica package for symbolic evaluation of Feynman diagrams, we have created a powerful framework for automatizing calculations in nonrelativistic EFTs (NREFTs) at tree- and 1-loop level. This is achieved by exploiting the novel features of FeynCalc that support manipulations of Cartesian tensors, Pauli matrices and nonstandard loop integrals. Additional operations that are common in nonrelativistic EFT calculations are implemented in a dedicated add-on called FeynOnium. While our current focus is on EFTs for strong interactions of heavy quarks, extensions to other systems that admit a nonrelativistic EFT description are planned for the future. All our codes are open-source and publicly available. Furthermore, we provide several example calculations that demonstrate how FeynOnium can be employed to reproduce known results from the literature.
Comments:
61 pages, no figures, matches the version accepted in JHEP. To obtain the programs, see https://github.com/FeynCalc
Subjects:
High Energy Physics — Phenomenology (hep-ph); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2006.15451 [pdf]
JHEP(2020)·23 citations
16
[Submitted on 28 Jun 2020] (cross-list from hep-ph)
Theoretical study of the $Ω (2012)$ state in the $Ω_{c}^{0} \to π^{+} Ω (2012)^{-} \to π^{+} (K ˉ Ξ)^{-}$ and $π^{+} (K ˉ Ξ π)^{-}$ decays
Chun-Hua Zeng🇨🇳 · Jun-Xu Lu🇨🇳 · En Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Li-Sheng Geng🇨🇳
We report on a theoretical study of the newly observed $Ω (2012)$ resonance in the nonleptonic weak decays of $Ω_{c}^{0} \to π^{+} K ˉ Ξ^{*} (1530) (η Ω) \to π^{+} (K ˉ Ξ)^{-}$ and $π^{+} (K ˉ Ξ π)^{-}$ via final-state interactions of the $K ˉ Ξ^{*} (1530)$ and $η Ω$ pairs. The weak interaction part is assumed to be dominated by the charm quark decay process: $c (ss) \to (s + u + d ˉ) (ss)$ , while the hadronization part takes place between the $sss$ cluster from the weak decay and a quark-antiquark pair with the quantum numbers $J^{P C} = 0^{++}$ of the vacuum, produces a pair of $K ˉ Ξ^{*} (1530)$ and $η Ω$ . Accordingly, the final $K ˉ Ξ^{*} (1530)$ and $η Ω$ states are in pure isospin $I = 0$ combinations, and the $Ω_{c}^{0} \to π^{+} K ˉ Ξ^{*} (1530) (η Ω) \to π^{+} (K ˉ Ξ)^{-}$ decay is an ideal process to study the $Ω (2012)$ resonance. With the final-state interaction described in the chiral unitary approach, up to an arbitrary normalization, the invariant mass distributions of the final state are calculated, assuming that the $Ω (2012)$ resonance with spin-parity $J^{P} = 3/ 2^{-}$ is a dynamically generated state from the coupled channels interactions of the $K ˉ Ξ^{*} (1530)$ and $η Ω$ in $s$ -wave and $K ˉ Ξ$ in $d$ -wave. We also calculate the ratio, $R_{K ˉ Ξ}^{K ˉ Ξ π} = Br [Ω_{c}^{0} \to π^{+} Ω (2012)^{-} \to π^{+} (K ˉ Ξ π)^{-}] / Br [Ω_{c}^{0} \to π^{+} Ω (2012)^{-} \to π^{+} (K ˉ Ξ)^{-}$ ]. The proposed mechanism can provide valuable information on the nature of the $Ω (2012)$ and can in principle be tested by future experiments.
Comments:
More references and discussions are added; typos are fixed
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2006.15547 [pdf]
PRD(2020)·35 citations
17
[Submitted on 28 Jun 2020] (cross-list from hep-ph)
In medium properties of axion within a Polyakov loop enhanced Nambu-Jona-Lasinio model
Arpan Das🇵🇱 · Hiranmaya Mishra🇮🇳 · Ranjita K. Mohapatra🇮🇳
We estimate the axion properties i.e. its mass, topological susceptibility and the self-coupling within the framework of Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model at finite temperature and quark chemical potential. PNJL model, where quarks couple simultaneously to the chiral condensate and to a background temporal quantum chromodynamics (QCD) gauge field, includes two important features of QCD phase transition, i.e. deconfinement and chiral symmetry restoration. The Polyakov loop in PNJL model plays an important role near the critical temperature. We have shown significant difference in the axion properties calculated in PNJL model compared to the same obtained using Nambu-Jona-Lasinio (NJL) model. We find that both the mass of the axion and its self-coupling are correlated with the chiral transition as well as the confinement-deconfinement transition. We have also estimated the axion properties at finite chemical potential. Across the QCD transition temperature and/or quark chemical potential axion mass and its self-coupling also changes significantly. Since the PNJL model includes both the fermionic sector and the gauge fields, it can give reliable estimates of the axion properties, i.e. it's mass and the self-coupling in a hot and dense QCD medium. We also compare our results with the lattice QCD results whenever available.
Comments:
23 pages, 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2006.15727 [pdf]
PRD(2021)·19 citations
18
[Submitted on 29 Jun 2020] (cross-list from physics.data-an)
Pileup corrections on higher-order cumulants
Toshihiro Nonaka🇯🇵 · Masakiyo Kitazawa🇯🇵 · ShinIchi Esumi🇯🇵
We propose a method to remove the contributions of pileup events from higher-order cumulants and moments of event-by-event particle distributions. Assuming that the pileup events are given by the superposition of two independent single-collision events, we show that the true moments in each multiplicity bin can be obtained recursively from lower multiplicity events. In the correction procedure the necessary information are only the probabilities of pileup events. Other terms are extracted from the experimental data. We demonstrate that the true cumulants can be reconstructed successfully by this method in simple models. Systematics on trigger inefficiencies and correction parameters are discussed.
Comments:
11 pages, 8 figures
Subjects:
Data Analysis, Statistics and Probability (physics.data-an); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2006.15809 [pdf]
Nucl.Instrum.Meth.A(2020)·18 citations
19
[Submitted on 29 Jun 2020] (cross-list from gr-qc)
Hawking radiation from acoustic black holes in relativistic heavy ion collisions
Arpan Das🇮🇳 · Shreyansh S. Dave🇮🇳 · Oindrila Ganguly🇮🇳 · Ajit M. Srivastava🇮🇳
We propose a new analogue model of gravity - the evolving quark gluon plasma (QGP) produced in relativistic heavy ion collisions. This quark gluon plasma is the "most inviscid" fluid known. Such low kinematic viscosity is believed to reflect strongly correlated nature for QGP in these experiments. Hence, it may provide a good example of a quantum fluid naturally suited to studies of acoustic Hawking radiation. Due to rapid longitudinal expansion, presence of a sonic horizon is also naturally guaranteed here, though, in general, this horizon is not static. Using Ultra relativistic quantum molecular dynamics (UrQMD) simulations, we show that, under certain conditions, the longitudinal velocity of the plasma, near the sonic horizon, can become time independent for a short span during the evolution of the system. During this period, we can have a conformally static acoustic metric with a (conformal) Killing horizon coinciding with the apparent horizon. An asymptotic observer will then see a thermal flux of phonons, constituting the Hawking radiation, coming from the horizon. For the relatively low energy collision considered here, where the resulting QCD system is governed by non-relativistic hydrodynamics, we estimate the Hawking temperature to be about 4-5 MeV (with the temperature of the QCD fluid being about 135 MeV). We discuss the experimental signatures of this Hawking radiation in terms of a thermal component in the rapidity dependence of the transverse momentum distribution of detected particles. We also discuss extension to ultra-relativistic case which should lead to a higher Hawking temperature, along with the effects of dynamical horizon leading to blue/red shift of the temperature.
Comments:
10 pages, 2 figures: Text modified or clarified in places, new references added
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2006.15912 [pdf]
PLB(2021)·7 citations
20
[Submitted on 29 Jun 2020] (cross-list from hep-ph)
Fermion and Photon gap-equations in Minkowski space within the Nakanishi Integral Representation method
Cédric Mezrag🇮🇹 · Giovanni Salmè🇮🇹
The approach based on the Nakanishi integral representation of n-leg transition amplitudes is extended to the treatment of the self-energies of a fermion and an (IR-regulated) vector boson, in order to pave the way for constructing a comprehensive application of the technique to both gap- and Bethe-Salpeter equations, in Minkowski space. The achieved result, namely a 6-channel coupled system of integral equations, eventually allows one to determine the three Källén-Lehman weights for fully dressing the propagators of fermion and photon. A first consistency check is also provided. The presented formal elaboration points to embed the characteristics of the non-perturbative regime at a more fundamental level. It yields a viable tool in Minkowski space for the phenomenological investigation of strongly interacting theories, within a QFT framework where the dynamical ingredients are made transparent and under control.
Comments:
35 pages, 9 figures, accepted in EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2006.15947 [pdf]
EPJC(2021)·26 citations
21
[Submitted on 29 Jun 2020] (cross-list from hep-th)
Out of equilibrium Chiral Vortical Effect in Holography
Sergio Morales-Tejera🇪🇸 · Karl Landsteiner🇪🇸
We study the chiral vortical effect far from equilibrium in a strongly coupled holographic field theory. Rotation is represented as a perturbation via a gravito-magnetic field on top of a five-dimensional charged AdS Vaidya metric. We also introduce a momentum relaxation mechanism by linear scalar field backgrounds and study the CVE dynamics as function of the charges, temperature and momentum relaxation. The far from equilibrium behavior shows that the CVE builds up with a significant delay in time compared to the quasi instantaneous equilibration of the background metric. We also pay special attention to the effects of the gravitational contribution to the axial anomaly in the CVE of the axial current. We develop an analytic estimate of this delay and also compute the quasi-normal modes near equilibrium which determine the late time ring down.
Comments:
39 pages, 22 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2006.16031 [pdf]
PRD(2020)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE