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Nuclear Theory·nucl-th

Monday·December 22, 2025

14 papers—7 primary·7 cross-listed

All14Primary7Cross-lists7
  1. 01

    [Submitted on 19 Dec 2025]

    Dynamical equation for quark spin polarization in the rotating medium

    Tianyang Li🇨🇳 · Yunfei Fan🇺🇸 · Anping Huang🇨🇳 · Baoyi Chen🇨🇳

    In non-central relativistic heavy-ion collisions, the produced quark-gluon plasma (QGP) behaves approximately as a rotating fluid due to the system's initial angular momentum. In this rotating fluid, the spins of quarks become polarized due to the coupling between spin and angular momentum, as well as random spin-spin interactions. Since the Landau-Lifshitz (LL) equation effectively describes the spin polarization of fermions in a medium with a magnetic field, we derive a phenomenological equation analogous to the LL equation for heavy quark spin dynamics in the rotating medium. The spin-angular momentum coupling and random spin-spin interactions are incorporated, leading to a detailed balance of heavy quark spin distributions. This equation provides insight into the spin dynamics of heavy quarks and quarkonium in relativistic heavy-ion collisions.

    Comments:
    6 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2512.17230 [pdf]
    PRD(2026)·1 citation
  2. 02

    [Submitted on 19 Dec 2025]

    Systematic analysis of proton- and deuteron-induced one-proton knockout reactions

    Hibiki Nakada · Shoya Ogawa · Yoshiki Chazono · Kazuyuki Ogata

    The ratios of the one-proton knockout cross sections by a deuteron to those by a proton are about 1.5, indicating that using deuteron is more efficient than proton in yielding large knockout cross sections. However, this ratio differs from the intuitive expectation, and its underlying mechanism remains unclear. The purpose of this study is to clarify the mechanism behind the observed ratio by theoretically describing and analyzing the deuteron- and proton-induced one-proton knockout reactions. Proton-induced one-proton knockout reactions are described within the standard distorted-wave impulse approximation (DWIA) framework, while deuteron-induced one-proton knockout reactions are treated with a new approach, DWIA-BU, that incorporates deuteron breakup into the DWIA. The ratios calculated with the DWIA-BU reproduce the experimental data reasonably, whereas those with the DWIA significantly underestimate them. The ratio of the corresponding elementary cross sections remains about 3.5 regardless of the energy, and the difference in absorption between the deuteron and the proton influences the ratios of knockout cross sections, resulting in agreement between the calculated ratios and the experimental data. It is found that the deuteron breakup is essential to reproduce the experimental ratio. The ratios of the knockout cross sections are primarily determined by the difference in the elementary cross sections and that in the absorption between the deuteron and the proton.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2512.17236 [pdf]
    J.Phys.Soc.Jap.(2026)·0 citations
  3. 03

    [Submitted on 19 Dec 2025]

    From closed shells to open shells: Coupled-cluster calculations of atomic nuclei

    F. Marino🇩🇪 · F. Bonaiti🇺🇸 · P. Demol🇧🇪 · S. Bacca🇩🇪 · T. Duguet🇧🇪 · G. Hagen🇺🇸 · G. R. Jansen🇺🇸 · T. Papenbrock🇺🇸 · A. Tichai🇩🇪

    Coupled-cluster theory is a powerful tool for first-principles calculations of atomic nuclei, enabling accurate predictions of nuclear observables across the Segrè chart. While coupled-cluster computations are especially efficient at shell closures, extensions have been developed to tackle open-shell nuclei, by exploiting the equation-of-motion method or by expanding the coupled-cluster wave function on top of a symmetry-breaking (either deformed or superfluid) reference state. In this study, we provide a comprehensive comparison of these different formulations applied to the calcium and nickel isotopes using nuclear two- and three-body interactions from chiral effective field theory. Based on ground-state energies, two-neutron separation energies, and two-neutron shell gaps, different coupled-cluster computations - based on symmetry-broken reference states and equation-of-motion techniques - offer consistent descriptions of bulk properties across medium-mass isotopic chains.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2512.17311 [pdf]
    PRC(2026)·6 citations
  4. 04

    [Submitted on 19 Dec 2025]

    Kinetic-Theory Bounds on the Equation of State of Dense QCD Matter

    Michał Marczenko🇵🇱

    We derive bounds on the equation of state of cold, dense matter by extending the causal, model-agnostic interpolation between chiral effective field theory and perturbative calculations with a microscopic constraint from relativistic kinetic theory. The additional condition restricts the stiffest admissible behavior of the equation of state and systematically reduces the range of allowed equations of state, with the strongest effect at high densities. The resulting bounds remain consistent with known low- and high-density limits, while the strength of the constraint depends on the density above which the kinetic-theory condition is applied. These bounds can be readily incorporated into future studies of cold, dense matter and used to assess the impact of microscopic stability conditions on equation-of-state inference.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2512.17410 [pdf]
    PRC(2026)·1 citation
  5. 05

    [Submitted on 19 Dec 2025]

    Towards a fluid-dynamic description of an entire heavy-ion collision: from the colliding nuclei to the quark-gluon plasma phase

    Andreas Kirchner🇺🇸 · Federica Capellino🇩🇪 · Eduardo Grossi🇮🇹 · Stefan Floerchinger🇮🇹

    The fluid-dynamical modeling of a nuclear collision at high energy usually starts shortly after the collision. A major source of uncertainty comes from the detailed modeling of the initial state. While the collision itself likely involves far-from-equilibrium dynamics, it is not excluded that a fluid theory of second order can reasonably well describe its soft features. Here we explore this possibility and discuss how the state before the collision can be described in that setup, examine the required fluid-dynamical equations of motion and study the resulting entropy production. While we do here only first steps, we outline a larger program, which could lead to a dynamical description of heavy-ion collisions where the only uncertainty lies in the thermodynamic and transport properties of quantum chromodynamics.

    Comments:
    Proceedings for Quark Matter 2025
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2512.17651 [pdf]
    EPJ Web Conf.(2026)·0 citations
  6. 06

    [Submitted on 19 Dec 2025]

    Reduced basis emulator for elastic scattering in continuum-discretized coupled-channels calculations

    Jin Lei

    I develop a reduced basis emulator for continuum-discretized coupled-channel (CDCC) calculations that achieves speedups of while maintaining sub-percent accuracy. The emulator is constructed using the proper orthogonal decomposition (POD) method applied to snapshots of CDCC solutions computed at sampled points in the optical potential parameter space. The prediction is performed via Galerkin projection onto the reduced basis. I demonstrate the method using deuteron scattering on Ni at 21.6 MeV as a test case, emulating 18 optical potential parameters simultaneously. The emulator reproduces elastic scattering cross sections with errors below 0.1% across a wide parameter range. This development enables efficient uncertainty quantification and Bayesian parameter estimation for nuclear reaction calculations that were previously computationally prohibitive.

    Comments:
    12 pages, 7 figures. Published version
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2512.17687 [pdf]
    PRC(2026)·7 citations
  7. 07

    [Submitted on 19 Dec 2025]

    Active learning emulators for nuclear two-body scattering in momentum space

    A. Giri🇺🇸 · J. Kim🇺🇸 · C. Drischler🇺🇸 · Ch. Elster🇺🇸 · R. J. Furnstahl🇺🇸

    We extend the active learning emulators for two-body scattering in coordinate space with error estimation, recently developed by Maldonado et al. [Phys. Rev. C 112, 024002], to coupled-channel scattering in momentum space. Our full-order model (FOM) solver is based on the Lippmann-Schwinger integral equation for the scattering -matrix as opposed to the radial Schrödinger equation. We use (Petrov-)Galerkin projections and high-fidelity calculations at a few snapshots across the parameter space of the interaction to construct efficient reduced-order models (ROMs), trained by a greedy algorithm for locally optimal snapshot selection. Both the FOM solver and the corresponding ROMs are implemented efficiently in Python using Google's JAX library. We present results for emulating scattering phase shifts in coupled and uncoupled channels and cross sections, and assess the accuracy of the developed ROMs and their computational speedup factors. We also develop emulator error estimation for both the -matrix and the total cross section. The software framework for reproducing and extending our results is publicly available. Together with our recent advances in developing active-learning emulators for three-body scattering, these emulator frameworks set the stage for full Bayesian calibrations of chiral nuclear interactions and optical models against scattering data with quantified emulator errors.

    Comments:
    20 pages, 9 figures, 1 Table; minor corrections; close to published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Data Analysis, Statistics and Probability (physics.data-an)
    arXiv:
    2512.17842 [pdf]
    PRC(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE