Nuclear Theory·nucl-th

Wednesday·August 10, 2022

10 papers—5 primary·5 cross-listed

01
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.
nucl-thhep-phPLB(2023)·1 citation
02
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.
nucl-thhep-phActa Phys.Polon.Supp.(2023)·9 citations
03
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 $N = 104$ .
nucl-thastro-ph.SRnucl-exPRC(2022)·100 citations
04
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.
nucl-thhep-exhep-phnucl-exPRC(2023)·4 citations
05
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.
nucl-thEPJ Web Conf.(2022)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Hadronic J/ψ Regeneration in Pb+Pb Collisions

Spin-thermal shear coupling in relativistic nuclear collisions

Nuclear mass predictions with machine learning reaching the accuracy required by r-process studies

Thermal fluctuations on the freeze-out surface of heavy-ion collisions and their impact on particle correlations

SU(3)_f Constraints on Hypernuclear Energy Density Functionals

Affiliations

Hadronic $J / ψ$ Regeneration in Pb+Pb Collisions

Nuclear mass predictions with machine learning reaching the accuracy required by $r$ -process studies