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Nuclear Theory·nucl-th

Thursday·January 29, 2026

8 papers—5 primary·3 cross-listed

All8Primary5Cross-lists3
  1. 01

    [Submitted on 27 Jan 2026]

    Exploring the properties of the Hadronic Phase in Heavy-Ion Collisions at RHIC Energies via Partial Chemical Equilibrium

    Rishabh Sharma · Chitrasen Jena · Volodymyr Vovchenko

    The hadronic phase in heavy-ion collisions plays a crucial role in shaping the final-state hadron abundances. In this work, we study Au+Au collisions at = 7.7-200 GeV using the Hadron Resonance Gas model in Partial Chemical Equilibrium (HRG-PCE). By fitting the yields of stable hadrons and short-lived resonances such as K, we extract both chemical and kinetic freeze-out temperatures as functions of center-of-mass energy and centrality. The analysis, performed using the Thermal-FIST package, avoids assumptions about radial flow profile or freeze-out hypersurfaces. Furthermore, we estimate the baryon annihilation freeze-out temperature from the experimentally measured p ratio, using the HRG-PCE framework extended to include reactions. The inferred annihilation freeze-out temperature lies between the chemical and kinetic freeze-out temperatures, suggesting that baryon annihilation remains active in the early hadronic phase but ceases prior to kinetic freeze-out. These results provide a consistent picture of the sequential decoupling of hadronic processes and demonstrate that inelastic hadronic interactions significantly influence the chemical composition of the system between chemical and kinetic freeze-outs at RHIC energies.

    Comments:
    14 pages, 10 figures (7 main + 3 in Appendix)
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2601.20065 [pdf]
    0 citations
  2. 02

    [Submitted on 28 Jan 2026]

    Baryon Transition Form Factors from Dynamical Coupled-Channel Analyses

    Yu-Fei Wang🇨🇳

    In this talk, the electromagnetic transition form factors from the nucleon ground state to twelve and states are exhibited and discussed. Those results are extracted through a comprehensive coupled-channel approach -- the Juelich-Bonn-Washington model, with the center-of-mass energy ranging from GeV to GeV, and the photon virtuality up to GeV. The extraction is based on electroproduction data points of , , and channels, with additionally about data points in the hadronic sector as well as photoproductions as boundary conditions. The form factors are defined from the residues at the corresponding resonance poles in the multipole amplitudes. Uncertainties are also estimated by the exploration of the parameter space. The qualitative behavior of the transition form factors of and here are in agreement with the previous studies, while for the other states, there has not been literature results that are also defined at the resonance poles.

    Comments:
    7 pages, 2 figures, conference proceeding of the 21st International Conference on Hadron Spectroscopy and Structure (HADRON2025), already published
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2601.20188 [pdf]
    PoS(2026)·0 citations
  3. 03

    [Submitted on 28 Jan 2026]

    From first to second minimum: Parity-dependent level densities in Pu

    A. Rahmatinejad · T. M. Shneidman · N. Jovancevic

    We calculate the parity-dependent level density ratios for Pu across a broad range of quadrupole deformations, from the spherical configuration up to the superdeformed region, explicitly including both the ground-state minimum and the second minimum (fission isomer). The parity-equilibration energy, defined as the excitation energy at which positive- and negative-parity level densities approach equilibrium, is compared between configurations. A significant reduction is observed near the second minimum, indicating a faster equilibration process in this region.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2601.20329 [pdf]
    0 citations
  4. 04

    [Submitted on 28 Jan 2026]

    Effects of the centrality determination method for the equation of state and nucleonic observables from Au+Au collisions at = 2.4 GeV

    Xiaoqing Yue🇨🇳 · Pengcheng Li🇨🇳 · Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳 · Fuhu Liu🇨🇳

    Centrality determination remains one of the major sources of systematic uncertainty in intermediate-energy heavy-ion collision analyses, especially for probing the nuclear equation of state (EoS) at supra-saturation densities. To quantitatively assess the uncertainties associated with different centrality determination methods and to investigate their effects on final-state EoS-sensitive observables. Within the ultra-relativistic quantum molecular dynamics (UrQMD) model, Au+Au collisions at =2.4 GeV are performed within a soft and a hard EoS. Event centrality is determined using the multiplicity of all charged particles () and two impact parameter-based centrality filters, one based on a geometrical interpretation and the other based on the Glauber Monte Carlo (MC) model, denoted as and , respectively. It is shown that there exist significant differences between the real impact parameter distributions of event samples selected by , , and , particularly between and . When the is employed, uncertainties associated with centrality selection have a weaker influence on observables than the effects induced by the EoS. In contrast, when the is used, the influence of centrality-related uncertainties becomes more pronounced than that of the EoS. These results demonstrate that a rigorous and consistent mapping between and impact parameter is essential to impose quantitative constraints on the high-density nuclear EoS. Furthermore, our study indicates that the geometrical interpretation of centrality remains valid and consistent with dynamical multiplicity selection, whereas the Glauber MC-based centrality determination becomes unreliable at the investigated energy.

    Comments:
    10 pages, 8 figures. Accepted for publication in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2601.20491 [pdf]
    PRC(2026)·2 citations
  5. 05

    [Submitted on 28 Jan 2026]

    De-excitation effects on entanglement in multi-nucleon transfer reactions

    Y. C. Yang · D. D. Zhang · D. Vretenar · B. Li · T. Nikšić · P. W. Zhao · J. Meng

    This study quantifies the impact of nuclear de-excitation on correlations in multi-nucleon transfer (MNT) reactions. To bridge the gap between initial collision dynamics and final experimental observables, we introduce a hybrid TDCDFT+GEMINI approach, integrating time-dependent covariant density functional theory (TDCDFT) with the statistical de-excitation model GEMINI++. Applied to the Ca + Pb reaction, our method demonstrates that the de-excitation is essential for reconciling theoretical cross sections with experimental data. Analysis of the cross-section Shannon entropy reveals that new reaction channels open abruptly at a specific energy threshold. By employing mutual information, we show that the de-excitation process significantly degrades the initial quantum entanglement between the projectile-like and the target-like fragments, revealing a key mechanism through which fundamental quantum correlations are lost.

    Comments:
    25 pages, 5 figures, has been accepted by Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2601.20535 [pdf]
    PRC(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE