Nuclear Theory·nucl-th

Wednesday·February 26, 2025

17 papers—8 primary·9 cross-listed

01
[Submitted on 24 Feb 2025]
Renormalization group analysis of electromagnetic properties of the deuteron
Thomas R. Richardson🇩🇪 · Immo C. Reis🇩🇪
The role of radiative corrections in low energy nuclear physics is beginning to receive more scrutiny. We examine the impact of these corrections for the deuteron charge form factor and the radiative capture process $n p \to d γ$ through the velocity renormalization group. In both cases, we find percent level shifts in the relevant observables after evolving the subtraction velocity to the typical velocity of nucleons in the bound state. This suggests that electromagnetic corrections constitute a non-negligible source of uncertainty in existing few-body calculations.
Comments:
26 pages, 9 figures, version published in Physical Review C 111
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2502.17634 [pdf]
PRC(2025)·3 citations
02
[Submitted on 24 Feb 2025]
Neural network-based prediction of particle-induced fission cross sections for r-process nucleosynthesis trained with dynamical reaction models
J.L. Rodríguez-Sánchez · G. García-Jiménez · H. Alvarez-Pol · M. Feijoo-Fontán · A. Graña-González
Large-scale computations of fission properties play a crucial role in nuclear reaction network calculations simulating rapid neutron-capture process (r-process) nucleosynthesis. Due to the large number of fissioning nuclei contributing to the r-process, a description of particle-induced fission reactions is computationally challenging. In this work, we use theoretical calculations based on the INCL+ABLA models to train neural networks (NN). The results for the prediction of proton-induced spallation reactions, in particular fission, utilizing a large variety of NN models across the hyper-parameter space are presented, which are relevant for r-process calculations.
Comments:
3 pages, 1 figure, NN2024 conference
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2502.17700 [pdf]
NPA(2025)·0 citations
03
[Submitted on 25 Feb 2025]
Dynamical evolution of critical fluctuations with second-order baryon diffusion coupled to chiral condensate
Azumi Sakai🇯🇵 · Koichi Murase🇯🇵 · Hirotsugu Fujii🇯🇵 · Tetsufumi Hirano🇯🇵
We develop a dynamical model to describe critical fluctuations in heavy-ion collisions, incorporating the baryon diffusion current and chiral condensate as dynamical degrees of freedom, to address their nontrivial scale separation. The model couples fluctuations of the chiral condensate $σ$ with baryon density fluctuations $n$ and the diffusion current $ν$ based on a second-order diffusion equation with a finite relaxation time of the baryon diffusion $τ_{R}$ . We analyze the spacetime evolution and these correlation functions of the fluctuations in one-dimensionally expanding background. We confirm that an appropriate relaxation time $τ_{R}$ ensures causality. We show that propagating waves with finite $τ_{R}$ split into two modes at the critical temperature due to a rapid change of kinetic coefficients. In the correlation functions, we find that dynamical $σ$ blurs the structure and peak around the critical temperature. With finite $τ_{R}$ , the effect of the critical fluctuations persists longer into the later stages of the evolution. These findings suggest importance of dynamical effects of the chiral condensate and baryon diffusion current in identifying critical-point signals in heavy-ion collisions, where the scale separation is nontrivial.
Comments:
28 pages, 18 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2502.17791 [pdf]
PRC(2025)·1 citation
04
[Submitted on 25 Feb 2025]
Hybrid stars with large quark cores within the parity doublet model and modified NJL model
Wen-Li Yuan🇨🇳 · Bikai Gao🇯🇵 · Yan Yan🇨🇳 · Renxin Xu🇨🇳
Using the parity doublet model (PDM) for hadronic matter and a modified Nambu-Jona-Lasinio (NJL) model for quark matter, we investigate the potential existence of two- and three-flavor quark matter in neutron star cores. Both models respect chiral symmetry, and a sharp first-order phase transition is implemented via Maxwell construction. We find stable neutron stars with quark cores within a specific parameter space that satisfies current astronomical observations. Typical neutron stars with masses around $1.4 M_{⊙}$ may possess deconfined quark matter in their centers. The hybrid star scenario with a two-flavor quark core offers enough parameter space to allow the neutron stars with large quark cores exceeding $\sim 1 M_{⊙}$ , and allow the early deconfinement position before $2 ρ_{0}$ , where $ρ_{0}$ is the nuclear saturation density. The observations of gravitational wave event GW170817 suggest a relatively large chiral invariant mass $m_{0} = 600 MeV$ in the PDM for scenarios involving three-flavor quark matter cores. The maximum mass of the hybrid star with a quark core is found to be approximately $2.2 M_{⊙}$ for both two- or three-flavor quark matter in their centers.
Comments:
17 pages, 7 figures, PRD published
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2502.17859 [pdf]
PRD(2025)·18 citations
05
[Submitted on 25 Feb 2025]
Stellar weak rates of the $r p$ -process waiting points: Effects of strong magnetic fields
Qi-Ye Hu · Long-Jun Wang · Yang Sun
Incorporating microscopic nuclear-structure information into the discussion of bulk properties of astronomical objects such as neutron stars has always been a challenging issue in interdisciplinary nuclear astrophysics. Using the $r p$ -process nucleosynthesis as an example, we studied the effective stellar $β^{+}$ and electron capture (EC) rates of eight waiting-point (WP) nuclei with realistic stellar conditions and presence of strong magnetic fields. The relevant nuclear transition strengths are provided by the projected shell model. We have found that, on average, due to the magnetic field effect, the $β^{+}$ and EC rates can increase by more than an order of magnitude for all combinations of density and temperature, as well as in each of WPs studied. We relate the onset field strength, at which the weak rates begin to increase, to nuclear structure quantities, $Q$ value or electronic chemical potential $μ_{e}$ . The enhanced weak rates may change considerably the lifetime of WPs, thereby modifying the current understanding of the $r p$ -process.
Subjects:
Nuclear Theory (nucl-th); Astrophysics of Galaxies (astro-ph.GA)
arXiv:
2502.17953 [pdf]
PRL(2025)·5 citations
06
[Submitted on 25 Feb 2025]
Microscopic study of halo nuclei through (p,t) reactions
Pierre Descouvemont
We analyze (p,t) two-neutron transfer reactions in a semi-microscopic model. The overlap integrals of the target nucleus are calculated in a microscopic cluster model. The Resonating Group Method (RGM) assumes a cluster structure of the nucleus, and is well adapted to halo nuclei since the long-range part of the wave function is accurately described. We focus on (p,t) reactions involving 6He and 11Li, which are well known core+n+n halo nuclei. The RGM is based on a nucleon-nucleon interaction, and therefore does not involve any fitting procedure. It also provides overlap integrals of excited states of the core nucleus. We present overlap integrals and spectroscopic factors of 6He and 11Li. We compute the 6He(p,t)alpha and 11Li(p,t)9Li cross sections at the DWBA, and compare them with experiments. For 11Li we also determine the 11Li(p,t)9Li* cross section which involves the first excited states of 9Li. A fair agreement with experiment is obtained, considering that no parameter is adjusted.
Comments:
6 pages, 5 figures, accepted for publication in Physics Letters B
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2502.18043 [pdf]
PLB(2025)·1 citation
07
[Submitted on 25 Feb 2025]
Microscopic investigation of $E 2$ matrix elements in atomic nuclei
S.P. Rouoof · Nazira Nazir · S. Jehangir · G.H. Bhat · J.A. Sheikh · N. Rather · S. Frauendorf
A systematic analysis of $E 2$ matrix elements of $^{72}$ Ge, $^{76}$ Ge, $^{168}$ Er, $^{186}$ Os, $^{188}$ Os, $^{190}$ Os, $^{192}$ Os and $^{194}$ Pt nuclides is performed using the beyond mean-field approach of triaxial projected shell model (TPSM). For these nuclei, large sets of $E 2$ matrix elements have been deduced from the multi-step Coulomb excitation experiments, and it is shown that TPSM approach provides a reasonable description of the measured transitions. We have evaluated 1496 $E 2$ matrix elements up to spin, $I = 10$ for the eight nuclei studied, and tabulate them for future experimental and theoretical comparisons. Further, shape invariant analysis has been performed with the calculated $E 2$ transitions using the Kumar-Cline sum rules. It is inferred from the analysis that the resulting shape, after configuration mixing of the quasiparticle states, transforms from $γ$ -rigid to that of $γ$ -soft for some nuclei, in conformity with the experimental data.
Comments:
24 pages, 14 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2502.18076 [pdf]
PRC(2025)·3 citations
08
[Submitted on 25 Feb 2025]
Probing $Λ$ potential at high and low densities via $^3_{\Lambda}$H production in C+C reactions
Gao-Chan Yong🇨🇳 · J. L. Rodríguez-Sánchez🇪🇸 · Yapeng Zhang🇨🇳
The production of Lambda hyperons and light hypernuclei in heavy-ion collisions provides critical insights into the nuclear equation of state (EoS) and hyperon interactions in dense matter, addressing the longstanding ``hyperon puzzle'' in neutron star physics. Using the INCL+ABLA and AMPT-HC models, we systematically investigate C+C collisions at beam energies of 1.1 and 1.9 GeV/nucleon to explore the sensitivity of hyperon and hypernuclei yields to the EoS and hyperon potential. Our results reveal that Lambda hyperon production is predominantly influenced by the nuclear EoS, while light hypernuclei formation (e.g., $^3_{\Lambda}$H) exhibits stronger sensitivity to the hyperon potential at high/low densities with the incident beam energies of 1.1/1.9 GeV. The study provides a framework for future experiments at facilities like HIAF and FAIR/GSI to resolve the hyperon puzzle, thus advancing our understanding of quantum chromodynamics in high-density regimes.
Comments:
6 pages, 3 figures, 1 table, accepted by PRC, in production
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2502.18086 [pdf]
PRC(2025)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE