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Nuclear Theory·nucl-th

Thursday·December 4, 2025

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Astrophysical Reaction Rates for Charged-Particle Induced Reactions on Proton-Rich Nuclides

    Thomas Rauscher

    Astrophysical reaction rates for reactions with proton-rich isotopes of Ne to Bi from stability to the proton dripline were calculated with an updated version of the SMARAGD statistical model (Hauser-Feshbach) code. Here, the focus was on reactions with protons or particles as required for nucleosynthesis in proton-rich matter. For completeness, also neutron-induced reactions are provided for the same set of targets. Some comments on dependencies of rates on various nuclear properties and on the appropriate way to compare to experiments are given. The new rate set for charged-particle induced reactions provides a better description of experimental data than previously widely used rates, especially for reactions involving particles.

    nucl-thastro-ph.HEastro-ph.SREPJA(2026)·0 citations
  2. 02

    Initial state and evolution of hot and dense medium produced in isobaric collisions at 200A GeV at RHIC

    Amit Paul🇮🇳 · Rupa Chatterjee🇮🇳

    Isobaric collisions provide a unique opportunity to investigate how variations in the charge to mass ratio affect the final state observables produced in relativistic heavy ion collisions. Most importantly, isobaric systems that differ in their nuclear structure offer valuable insights into the underlying nuclear geometries, making them powerful tools to probe the role of nuclear structure using heavy ion collisions. We study the initial state and evolution of the hot and dense medium formed in Ru+Ru and Zr+Zr collisions at 200A GeV at RHIC using a relativistic hydrodynamical model. The initial geometry of the two isobaric collisions is found to influence the evolution of the hot and dense medium produced. The sensitivity of photon production, charged particle spectra and anisotropic flow coefficients () to the initial geometry, including different orientations of the isobaric set have been studied in detail. Significant variations in anisotropic flow of photons and hadrons are observed, highlighting the role of nuclear deformation in shaping final state observables. Moreover, photon anisotropic flow is found to be considerably more sensitive to the initial state than charged particle anisotropic flow, indicating that photon measurements in isobaric collisions have strong potential to constrain initial state modeling and improve our understanding of QGP properties in such systems.

    nucl-thPRC(2026)·1 citation
  3. 03

    Impact of octupole deformation on the nuclear electromagnetic response

    Manu Kanerva · Markus Kortelainen

    Background: Properties of giant dipole resonances, along with other nuclear resonances, provide valuable tools for refining theoretical models as they reflect collective features of nuclear matter. Among such collective phenomena is octupole deformation, whose impact on resonance features, however, is less studied. Purpose: Investigate the effect of reflection-symmetry-breaking octupole deformation on electric and magnetic transition strengths in atomic nuclei. Methods: Calculations were performed using linear response theory with the iterative finite amplitude method to solve quasiparticle random phase approximation-type equations. Underlying ground-state solutions were obtained within the framework of axially symmetric Skyrme-Hartree-Fock-Bogoliubov (HFB) using three different Skyrme functionals. Results: Electric and magnetic multipole responses were calculated for octupole-deformed even-even Rn, Ra, Th, U, Pu, and Cm isotopes. Calculations were performed on top of two distinct deformed ground-state solutions: one constrained to conserve parity, and the other allowing parity breaking. Sum rules were calculated from transition strengths and compared with the expected correlations to certain ground-state properties. Conclusions: Based on our results, the octupole deformation has only a modest effect on the transition strengths in the resonances. In turn, transition strengths have a greater effect at lower energies (), which encourages further investigation. Isoscalar transition strength was confirmed to have a significant contribution from the rotational Nambu--Goldstone mode in the parity-breaking HFB solution, and thus, removing it was found necessary.

    nucl-thPRC(2026)·0 citations
  4. 04

    Generalized Beth--Uhlenbeck entropy formula from the derivable approach

    David Blaschke🇵🇱 · Gerd Röpke🇩🇪 · Gordon Baym🇺🇸

    We derive a generalized Beth-Uhlenbeck formula for the entropy of a dense fermion system with strong two-particle correlations, including scattering states and bound states. We work within the derivable approach to the thermodynamic potential. The formula takes the form of an energy-momentum integral over a statistical distribution function times a unique spectral density. In the near mass-shell limit, the spectral density reduces, contrary to naïve expectations, not to a Lorentzian but rather to a "squared Lorentzian" shape. The relation of the Beth-Uhlenbeck formula to the -derivable approach is exact at the two-loop level for . The formalism we develop, which extends the Beth-Uhlenbeck approach beyond the low-density limit, includes Mott dissociation of bound states, in accordance with Levinson's theorem, and the self-consistent back reaction of correlations in the fermion propagation. We discuss applications to further systems, such as quark matter and nuclear matter.

    nucl-thhep-thphysics.plasm-phContrib.Plasma Phys.(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE