Nuclear Theory·nucl-th

Wednesday·August 10, 2022

10 papers—5 primary·5 cross-listed

01
[Submitted on 8 Aug 2022]
Hadronic $J / ψ$ Regeneration in Pb+Pb Collisions
Joseph Dominicus Lap🇺🇸 · Berndt Müller🇺🇸
We make use of published yields for $D$ -mesons and $J / ψ$ in Pb+Pb collisions at ALICE and a schematic description of the expansion of the hadron gas to study $D$ -meson collisions during the hadronic break-up phase as a production mechanism for charmonium in relativistic heavy ion collisions at the Large Hadron Collider. Our calculation is based on chemical reaction rates with thermal cross sections for an effective meson interaction among pseudoscalar and vector mesons. We find that due to regeneration, the newly measured $J / ψ$ yields are consistent with anywhere from roughly $25%$ to $110%$ of the total yield present at hadronization time. This allows us to bound the fractional abundance of $J / ψ$ immediately after hadronization: $0.28 \leq \frac{d N _{0}^{J / ψ} / d y}{d N _{eq}^{J / ψ} / d y} \leq 1.13$ . Our results are robust under the relaxation of the particulars of our schematic description and imply that it will be difficult to distinguish regeneration during hadronization from regeneration by final-state hadronic interactions. Therefore, regeneration must be taken into account when modelling.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2208.04368 [pdf]
PLB(2023)·1 citation
02
[Submitted on 8 Aug 2022]
Spin-thermal shear coupling in relativistic nuclear collisions
M. Buzzegoli🇺🇸 · F. Becattini🇮🇹 · G. Inghirami🇩🇪 · I. Karpenko🇨🇿 · A. Palermo🇮🇹
The spin polarization measurements of particles emitted in heavy-ion collisions have opened the possibility for new phenomenological investigations of spin physics in relativistic fluids. The theoretical predictions of global polarization are in agreement with the data, but consistent discrepancies stand out for the local polarization. We show that the covariant theory of relativistic quantum fluids at local equilibrium implies an additional, non-dissipative contribution to the spin polarization vector, which is proportional to the thermal shear, which has been previously overlooked. This additional contribution, together with an improved approximation in the expansion of the local equilibrium density operator, restores the quantitative agreement between the theoretical predictions and the experimental data.
Comments:
6 pages, 2 figures, presented at the XXIXth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions (Quark Matter 2022). v2: Added ancillary files for the figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2208.04449 [pdf]
Acta Phys.Polon.Supp.(2023)·9 citations
03
[Submitted on 9 Aug 2022]
Nuclear mass predictions with machine learning reaching the accuracy required by $r$ -process studies
Z. M. Niu · H. Z. Liang
Nuclear masses are predicted with the Bayesian neural networks by learning the mass surface of even-even nuclei and the correlation energies to their neighbouring nuclei. By keeping the known physics in various sophisticated mass models and performing the delicate design of neural networks, the proposed Bayesian machine learning (BML) mass model achieves an accuracy of $84$ ~keV, which crosses the accuracy threshold of the $100$ ~keV in the experimentally known region. It is also demonstrated the corresponding uncertainties of mass predictions are properly evaluated, while the uncertainties increase by about $50$ ~keV each step along the isotopic chains towards the unknown region. The shell structures in the known region are well described and several important features in the unknown region are predicted, such as the new magic numbers around $N = 40$ , the robustness of $N = 82$ shell, the quenching of $N = 126$ shell, and the smooth separation energies around $N = 104$ .
Comments:
14 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2208.04783 [pdf]
PRC(2022)·100 citations
04
[Submitted on 9 Aug 2022]
Thermal fluctuations on the freeze-out surface of heavy-ion collisions and their impact on particle correlations
Adrian Skasberg Aasen🇩🇪 · Stefan Floerchinger🇩🇪 · Giuliano Giacalone🇩🇪 · Deniz Guenduez🇩🇪
Particle momentum distributions originating from a quark-gluon plasma as produced in high-energy nuclear collisions can be influenced by thermal fluctuations in fluid dynamic fields. We study this effect by generalizing the commonly used kinetic freeze-out prescription by allowing for small fluctuations around an average in fluid velocity, chemical potentials and temperature. This leads to the appearance of specific two-body momentum correlations. Combining a blast-wave parametrization of the kinetic freeze-out surface with the thermal correlation functions of an ideal resonance gas, we perform an exploratory study of angular net-charge correlations induced by thermal fluctuations around vanishing chemical potential. We note a diffusion of the near-side peak around $Δ y = Δ ϕ = 0$ induced by variances of different chemical potentials, which could be investigated experimentally.
Comments:
15 pages; 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2208.04806 [pdf]
PRC(2023)·4 citations
05
[Submitted on 9 Aug 2022]
SU(3)_f Constraints on Hypernuclear Energy Density Functionals
Horst Lenske🇩🇪 · Madhumita Dhar🇩🇪
A covariant hyper-nuclear energy density functional (EDF) is derived from in medium nucleon meson vertex functionals, assuring the proper description of nuclear mean-field dynamics. The fundamental SU(3) coupling constants for the mean-field relevant vector (m=V) and scalar (m=S) interactions as functionals of the total baryon density are determined. Scalar and vector potentials and the resulting hyperon mean-fields in asymmetric nuclear matter are constructed and discussed, addressing also effects from three-body interactions. \Lambda- \Sigma^0 mixing in asymmetric nuclear through the coupling to the background isovector mean-field is addressed.
Comments:
6 pages,4 figures, 14th International Conference on Hypernuclear and Strange Particle Physics Conference Proceedings (HYP2022)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.04916 [pdf]
EPJ Web Conf.(2022)·0 citations
06
[Submitted on 8 Aug 2022] (cross-list from hep-ph)
Hadronic structure on the light-front V. Diquarks, Nucleons and multiquark Fock components
Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸
This work is a continuation in our series of papers, that addresses quark models of hadronic structure on the light front, motivated by the QCD vacuum structure and lattice results. In this paper we focus on the importance of diquark correlations, which we describe by a quasi-local four-fermion effective 't Hooft interaction induced by instantons. The same interaction is also shown to generate extra quark-antiquark pair of the "sea". Its higher order iteration can be included via "pion-mediation": both taken together yield a quantitative description of the observed flavor asymmetry of antiquarks sea. Finally we discuss the final step needed to bridge the gap between hadronic spectroscopy and parton observables, by forward DGLAP evolution towards the chiral upper scale of $\sim 1 GeV^{2}$ .
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2208.04428 [pdf]
PRD(2023)·18 citations
07
[Submitted on 9 Aug 2022] (cross-list from nucl-ex)
Measurement of Light Nuclei Production in Heavy-ion Collisions by the STAR experiment
Hui Liu (for the STAR Collaboration)🇨🇳
In these proceedings, we present the measurements of centrality, transverse momentum and rapidity dependences of proton ( $p$ ) and light nuclei ( $d$ ( $d$ ), $t$ , $^{3} He$ ( $^{3} He$ ), and $^{4} He$ ) production in Au+Au collisions at $s_{NN}$ = 3 GeV, and isobaric (Ru+Ru and Zr+Zr) collisions at $s_{NN}$ = 200 GeV. The compound yield ratios in central collisions at 3 GeV are found to be larger than the transport model calculations. Furthermore, the kinetic freeze-out parameters at 3 GeV show a different trend compared to those of light hadrons ( $π$ , $K$ , $p$ ) at higher energies.
Comments:
6 pages, 5 figures, contribution to XXIXth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions (QM 2022)
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2208.04650 [pdf]
Acta Phys.Polon.Supp.(2023)·8 citations
08
[Submitted on 9 Aug 2022] (cross-list from hep-ph)
Momentum broadening of heavy quarks and jets in the Glasma from classical colored particle simulations
Dana Avramescu🇷🇴 · Virgil Băran🇷🇴 · Vincenzo Greco🇦🇹 · Andreas Ipp🇦🇹 · David. I. Müller🇮🇹 · Marco Ruggieri🇨🇳
We investigate the effects of the pre-equilibrium Glasma stage of heavy-ion collisions on the broadening of momentum for heavy quarks and jets using classical colored particle simulations based on Wong's equations. Confirming previous studies, we find that these probes accumulate momentum on the order of the saturation scale $Q_{s}$ and that the color field of the Glasma induces an anisotropy with more broadening along the beam axis. For quark jets the anisotropy is more pronounced at lower energies.
Comments:
4 pages, 1 figure, proceedings for the 29th International Conference on Ultra-relativistic Nucleus-Nucleus Collisions (Quark Matter 2022)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2208.04781 [pdf]
Acta Phys.Polon.Supp.(2023)·1 citation
09
[Submitted on 9 Aug 2022] (cross-list from hep-th)
Nucleon-nucleon potential from instanton holonomies
Chris Halcrow🇸🇪 · Derek Harland🇬🇧
We derive the nucleon-nucleon interaction from the Skyrme model using the instanton and product approximations to skyrmion dynamics. In doing so, we also calculate the classical potential and metric for skyrmion dynamics in each of the approximations. This is the first time they have been compared in detail and the results show major disagreements between the approximations. We derive the eight low energy nucleon-nucleon interaction potentials and compare them with the Paris model. For the instanton approximation we find strong negative isoscalar and isovector spin-orbit potentials, matching phenomenological models and our geometric intuition. Results for the other potentials are mixed, in part due to the zero pion mass limit used in this approximation.
Comments:
28 pages, 5 figures. Eight text files containing Mathematica/Maple code can be accessed by selecting "Download other formats"; for usage instructions, see article
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2208.04863 [pdf]
PRD(2022)·9 citations
10
[Submitted on 9 Aug 2022] (cross-list from astro-ph.HE)
Thermal Contributions to Primordial Nucleosynthesis
Samina Masood🇺🇸 · Jaskeerat Singh🇺🇸
Electron mass is known to modify at finite temperatures and densities. Weak nuclear processes have a great impact on electron mass which modifies in a statistical background. We demonstrate how the temperature change in electron mass is associated with beta decay in the early universe. Its precise contributions to the abundance of light elements in the early universe describe some of the details about nucleosynthesis. We employ the calculational scheme of the renormalization of QED to precisely compute the temperature dependence of electron mass during the nuclear processes. In this paper we precisely compute the concentration of electron and its mass change with temperature during nucleosynthesis and use it to describe the helium abundance, expansion rate and energy density of the universe during nucleosynthesis.
Comments:
14 pages, 11 figures and 3 tables
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2208.04896 [pdf]
Int.J.Mod.Phys.A(2025)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE