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Nuclear Theory·nucl-th

Monday·October 13, 2025

10 papers—7 primary·3 cross-listed

All10Primary7Cross-lists3
  1. 01

    Effect of Finite-Temperature -Decay Rates on the Rapid Neutron Capture Process

    Yukiya Saito · Ante Ravlić · Pranav Nalamwar · Rebecca Surman

    -decay is known to play an essential role in the rapid neutron capture process (-process) during equilibrium and freeze-out when the neutron-rich nuclei decay back to stability. Recent systematic theoretical studies on -decay at finite temperature indicated that under hot conditions (~GK), a significant acceleration of -decay rates is expected, especially for nuclei near stability. This corresponds to the early stage of the -process. In this study, we investigate the effect of the -decays in finite temperature using the rates calculated with the finite-temperature proton-neutron relativistic quasiparticle random-phase approximation (FT-PNRQRPA). We explore a variety of astrophysical conditions and find that the effect on the abundance pattern is significant in hot and moderately neutron-rich conditions such as are expected in magnetorotational supernovae. Accelerated -decay rates also increase the heating rate in the early phase, resulting in an additional modification of the final abundance pattern.

    nucl-thastro-ph.HEApJ(2026)·2 citations
  2. 02

    Thermal and Magnetic effects on Bulk Viscosity in Binary Neutron Star Mergers

    Pranjal Tambe🇮🇳 · Debarati Chatterjee🇮🇳 · Mark Alford🇺🇸 · Alexander Haber🇬🇧

    Astrophysical scenarios such as binary neutron star mergers, protoneutron stars, and core-collapse supernovae involve finite temperatures and strong magnetic fields. Previous studies on the effect of magnetic fields on flavor-equilibration processes relied on the Fermi surface approximation, which is not a reliable approximation in the neutrino-transparent regime of matter in supernovae or neutron star mergers. In a recent study, we went beyond the Fermi surface approximation, performing the full phase space integral to obtain direct Urca rates in a background magnetic field. In this work, we extend these calculations to incorporate the collisional broadening (modified Urca) contribution. We use the recently developed nucleon width approximation, which naturally includes the magnetic field dependence of all contributions. We demonstrate the impact of magnetic fields on the flavor-equilibrium condition for two finite-temperature equations of state with different direct Urca thresholds. We also study the impact of magnetic fields on the bulk viscous dissipation of density oscillations relevant in postmerger scenarios.

    nucl-thastro-ph.HEhep-phPRC(2026)·2 citations
  3. 03

    Indirect method for nuclear reactions and the role of the self energy

    Gregory Potel

    When a nuclear species (e.g., a nucleon or a deuteron nucleus) propagating freely is made to collide with a target nucleus, its trajectory is modified by exchanging variable amounts of energy, mass, linear and angular momentum with the target, according to its interaction with the nuclear medium. By addressing this perturbation away from the free path, one hopes to learn something about the nature of the medium through which our probe propagates. This is the essence of the experimental use of nuclear reactions for the purpose of gathering information about nuclear structure. In order to deal with the structure and the reaction aspects of a specific experiment on the same footing, it is therefore desirable to identify a theoretical construct that embodies the modification of the propagation of a particle in the medium with respect to the free case, and use it both for the determination of the nuclear spectrum (structure) and for the calculation of scattering observables (reaction). A candidate for such an object is the self energy, and we will try in the present lectures to put it at the center stage in the formulation of scattering theory.

    nucl-th0 citations
  5. 05

    Temperature dependence of the nucleon-nucleon inelastic cross section in an isospin-asymmetric nuclear medium

    Manzi Nan🇨🇳 · Pengcheng Li🇨🇳 · Guojun Wei🇨🇳 · Xilong Xiang🇨🇳 · Wei Zuo🇨🇳 · Qingfeng Li🇨🇳

    The nucleon-nucleon () inelastic cross section plays an important role in constraining the nuclear equation of state at high baryon density and in describing the formation and evolution of compact astrophysical objects. In this study, the temperature dependence of the and production cross sections in the isospin-symmetric and -asymmetric nuclear medium is investigated within the self-consistent and relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) framework. Two relativistic mean-field parameterizations are employed: the density-dependent parameterization (called DD-ME) and the nonlinear-dependent parameterization (called OMEG). Both parameterizations yield similar -dependent baryon effective masses and mass splittings, although the OMEG set exhibits a stronger density dependence, particularly at higher densities (). Consequently, at lower densities, the energy, density, temperature, and isospin dependence of both and production cross sections are comparable for both sets, whereas at higher densities, the OMEG set predicts a stronger temperature and density sensitivity. Moreover, the dependence of the inelastic cross section is enhanced with increasing density, but is suppressed in isospin-asymmetric nuclear matter compared to that in isospin-symmetric nuclear matter. The isospin dependence of the cross section remains nearly -independent at small asymmetries, yet becomes more intricate in highly asymmetric systems. These findings provide valuable testing inputs for improving the thermal treatment of related dynamical processes in transport models and offer insights into the behavior of in astrophysical environments, such as core-collapse supernovae and binary neutron star mergers.

    nucl-th1 citation
  6. 06

    Entanglement and accidental symmetries in the nucleon-nucleon system

    Alma L. Cavallin🇸🇪 · Oliver Thim🇸🇪 · Christian Forssén🇸🇪

    We study the connection between accidental symmetries in the nuclear interaction and spin entanglement in two-nucleon scattering. Specifically, we incorporate different levels of Wigner and Serber symmetries into leading-order potentials derived from chiral effective field theory. We conduct a quantitative analysis by computing the full matrix, demonstrating that the neutron-proton spin entanglement can be related to the symmetry properties of the interaction and the presence of certain operators and partial waves. Furthermore, we study the order-by-order evolution of the spin entanglement, up to next-to-next-to-leading order in Weinberg power counting, for both neutron-proton and neutron-neutron scattering. Entanglement suppression is not observed in neutron-neutron scattering, which can be attributed to the Pauli principle and the absence of accidental symmetries in this system. We conclude that entanglement is a useful guide for studying the power counting and symmetries in nuclear interactions derived from effective field theories.

    nucl-thquant-phPRC(2026)·10 citations
  7. 07

    Probing the Dependence of Partonic Energy Loss on the Initial Energy Density of the Quark Gluon Plasma

    Ian Gill🇺🇸 · Ryan J. Hamilton🇺🇸 · Helen Caines🇺🇸

    Considerable evidence now exists for partonic energy loss due to interaction with the hot, dense medium created in ultra-relativistic heavy-ion collisions. A primary signal of this energy loss is the suppression of high transverse momentum hadron yields in A-A collisions relative to appropriately scaled collisions at the same energy. Measuring the collision energy dependence of this energy loss is vital to understanding the medium, but it is difficult to disentangle the medium-driven energy loss from the natural kinematic variance of the steeply-falling spectra across different . To decouple these effects, we utilize a phenomenologically motivated spectrum shift model to estimate the average transverse momentum loss imparted on high partons in A-A collisions, a proxy for the medium induced energy loss. We observe a striking correlation between and Glauber-derived estimates of initial state energy density , consistent across two orders of magnitude in collision energy for a variety of nuclear species. To access the path-length dependence of energy loss, we couple our model to geometric event shape estimates extracted from Glauber calculations to produce predictions for high- hadron elliptic flow that agree reasonably with data.

    nucl-thnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE