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Nuclear Theory·nucl-th

Wednesday·August 6, 2025

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 01

    [Submitted on 4 Aug 2025]

    Variations of the crossover and first-order phase transition curve in modeling the QCD equation of state

    Joseph I. Kapusta🇺🇸 · Shensong Wan🇺🇸

    Lattice QCD calculations have shown that the transition from hadrons to quarks and gluons is a rapid crossover at MeV at vanishing chemical potential. Many model calculations show that the transition is first-order at sufficiently high baryon chemical potential. It is then natural to expect the existence of a critical point where the crossover and first-order phase transition lines meet. We show how to embed a phase boundary that terminates at the critical point in a smooth background equation of state, using several different but closely related criteria, so as to yield the critical exponents and critical amplitude ratios expected of a transition in the 3D Ising and liquid-gas universality class. The crossover curves can be tuned to pass through experimental freeze-out data from heavy ion collisions at RHIC and the LHC. The resulting equations of state can be used in hydrodynamic simulations of these collisions to probe the existence of a critical point and corresponding first-order phase transition.

    Comments:
    9 pages, 16 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    2508.02845 [pdf]
    PRC(2026)·3 citations
  2. 02

    [Submitted on 5 Aug 2025]

    Response of asymmetric nuclear matter studied with a finite number of particles

    M. Li🇯🇵 · F. Marino🇩🇪 · G. Colò🇮🇹 · H. Liang🇯🇵

    We investigate the ground-state properties of asymmetric nuclear matter and its response to a static perturbation using the density functional theory framework. Our method, which extends the finite-nucleon-number technique of arXiv:2211.07986 to the case of isospin-asymmetric matter, allows to study the impact of external isoscalar and isovector fields on the system. In particular, the densities and static response functions in the different isospin channels, and as a function of isospin asymmetry, are evaluated. Finite-size effects are discussed by comparing with Random Phase Approximation predictions in the thermodynamic limit. A peculiar non-monotonic behavior of the isovector response function is analyzed.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2508.03114 [pdf]
    PRC(2026)·0 citations
  3. 03

    [Submitted on 5 Aug 2025]

    Machine Learning-Driven High-Precision Model for -Decay Energy and Half-Life Prediction of superheavy nuclei

    Qingning Yuan · Panpan Qi · Xuanpen Xiao · Xue Wang · Juan He · Guimei Long · Zhengwei Duan · Yangyan Dai · Runchao Yan · Gongming Yu · Haitao Yang

    Based on Extreme Gradient Boosting (XGBoost) framework optimized via Bayesian hyperparameter tuning, we investigated the {\alpha}-decay energy and half-life of superheavy nuclei. By incorporating key nuclear structural features-including mass number, proton-to-neutron ratio, magic number proximity, and angular momentum transfer-the optimized model captures essential physical mechanisms governing -decay. On the test set, the model achieves significantly lower mean absolute error (MAE) and root mean square error (RMSE) compared to empirical models such as Royer and Budaca, particularly in the low-energy region. SHapley Additive exPlanations (SHAP) analysis confirms these mechanisms are dominated by decay energy, angular momentum barriers, and shell effects. This work establishes a physically consistent, data-driven tool for nuclear property prediction and offers valuable insights into -decay processes from a machine learning perspective.

    Comments:
    21 pages, 8 tables, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2508.03155 [pdf]
    Phys.Scripta(2026)·4 citations
  4. 04

    [Submitted on 5 Aug 2025]

    Nonlinear analysis of causality for heat flow in heavy-ion collisions: constraints from equation of state

    Victor Roy🇮🇳

    The present work investigates the causal parameter space of the Mueller-Israel-Stewart second-order theory for heat-conducting fluids in the Eckart frame for one-dimensional fluid flow in systems with finite baryon density. It is shown that this parameter space is highly constrained and particularly sensitive to the equation of state and second-order transport coefficients. Through numerical analysis of the characteristic equations, the present analysis identifies regions of strong hyperbolicity, weak hyperbolicity, and non-hyperbolicity, mapping the boundaries of causality violation as functions of the heat flux to energy density ratio and relaxation parameters. The present work also explores the causality conditions using a realistic lattice QCD-based equation of state. Using the Navier-Stokes approximation, an estimate is made of the heat flow magnitude to assess causality criteria for one-dimensional heat conduction in heavy-ion collisions. The present calculations reveal unrealistically large heat flux values (--) for typical RHIC conditions when using thermal conductivity estimates from kinetic theory models, suggesting either significant overestimation of transport coefficients or breakdown of the fluid approximation in these extreme conditions. The pressure gradient corrections reduce the heat flow by approximately 15\% but do not resolve the causality concerns.

    Comments:
    12 pages, 6 figures, updated plots, text and references, added a new section. Published in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2508.03265 [pdf]
    PRC(2026)·2 citations
  5. 05

    [Submitted on 5 Aug 2025]

    Machine learning the single- hypernuclei with neural-network quantum states

    Zi-Xiao Zhang🇨🇳 · Yi-Long Yang🇨🇳 · Wan-Bing He🇨🇳 · Peng-Wei Zhao🇨🇳 · Bing-Nan Lu🇨🇳 · Yu-Gang Ma🇨🇳

    Single- hypernuclei are the most straightforward extension of atomic nuclei. A thorough description of baryonic system beyond first-generation quark sector is indispensable for the maturation of nuclear methods. This study pioneers the application of neural-network quantum states to hypernuclei, with trainable parameters determined by variational Monte Carlo approach (VMC-NQS). In order to reduce the numerical uncertainty and treat the nucleons and hyperons in a unified manner, spinor grouping (SG) method is proposed to analytically integrate out isospin degrees of freedom. A novel spin purification scheme is developed to address the severe spin contamination occurring in standard energy minimization due to the weakly bound characteristic of light single- hypernuclei. The energy spectrum of -shell hypernuclei is computed with one-thousandth level accuracy and benchmarked against existing stochastic variational results, showing superior performance. By comparing two different sets of Hamiltonian based on pionless effective field theory (pionless EFT), we choose an optimal model and further carry out calculations of selected -shell charge-symmetric hypernuclei with mass number up to 13, exhibiting satisfactory consistency with experimental results. Our findings underscore the potential of VMC-NQS family in approaching exact solution of few-body systems and the accuracy of pionless EFT in modeling hypernuclei. This is crucial for understanding hyperon-nucleon-nucleon and hyperon-hyperon-nucleon interactions, providing a powerful tool for precisely predicting the properties of multi-strangeness hypernuclei.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2508.03575 [pdf]
    PLB(2026)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE