Nuclear Theory·nucl-th

Thursday·December 4, 2025

7 papers—4 primary·3 cross-listed

01
[Submitted on 2 Dec 2025]
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 $α$ 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 $α$ particles.
Comments:
v2: expanded discussion, typos fixed; submitted to Europ. J. Phys A, Topical Issue "About Stars and Nuclei: Honoring the Legacy of Roberto Gallino"; 19 pages, 14 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2512.03206 [pdf]
EPJA(2026)·0 citations
02
[Submitted on 3 Dec 2025]
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 ( $v_{n}$ ) 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.
Comments:
9 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2512.03675 [pdf]
PRC(2026)·1 citation
03
[Submitted on 3 Dec 2025]
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 $M 1$ 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, $M 1$ transition strengths have a greater effect at lower energies ( $0 - 8 MeV$ ), which encourages further investigation. Isoscalar $E 3$ 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.
Comments:
17 pages, 14 figures, published in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2512.03776 [pdf]
PRC(2026)·0 citations
04
[Submitted on 3 Dec 2025]
Generalized Beth--Uhlenbeck entropy formula from the $Φ -$ 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 $Φ -$ 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 $Φ$ -derivable approach is exact at the two-loop level for $Φ$ . 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.
Comments:
10 pages, 3 figures, contribution to the special issue of "Contributions to Plasma Physics" on the occasion of the 65th birthday of Michael Bonitz
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th); Plasma Physics (physics.plasm-ph)
arXiv:
2512.03876 [pdf]
Contrib.Plasma Phys.(2026)·1 citation
05
[Submitted on 2 Dec 2025] (cross-list from hep-ph)
Effective Field Theory Perspective On King Non-linearity
Benoît Assi🇺🇸 · Sam Carey🇺🇸 · Sebastian Jäger🇬🇧 · Gabriel Lee🇨🇦 · Gil Paz🇺🇸 · Gilad Perez🇮🇱 · Jure Zupan🇺🇸
Precision spectroscopic measurements of isotope shifts have recently reached a high level of accuracy. Tests of King non-linearity (NL) along isotope chains have been proposed as a tool to search for fifth-force mediators. At the same time, these tests can potentially teach us about the structure of heavy nuclei at unprecedented precision, where King NL has already been observed in several systems. A robust interpretation of the existing data, however, is hampered by incomplete control over the Standard Model (SM) contributions. We develop a systematic effective field theory framework, matching the SM onto scalar non-relativistic QED in the infinite nuclear mass limit and then onto quantum-mechanical potentials. This approach organizes all nuclear effects into a small set of Wilson coefficients and cleanly separates short- and long-distance physics. We show that the commonly used treatment of the $⟨ r^{2} ⟩^{2}$ term needs to be reconsidered, as it arises only at second-order in perturbation theory, and we derive the long-range $1/ r^{4}$ potential from nuclear polarizability. Applying the framework to hydrogen-like systems, we provide a transparent classification of SM sources of King NL relevant for current and future isotope-shift experiments. The formalism can be applied to learn about the shape of the heavy scalar nuclei at a higher level of precision and detail than what was previously attainable.
Comments:
44 pages, 7 figures, v2: Typos corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2512.03157 [pdf]
1 citation
06
[Submitted on 3 Dec 2025] (cross-list from hep-ph)
Real-time evolution of critical modes in the QCD phase diagram
Yang-yang Tan🇨🇳 · Shi Yin🇩🇪 · Yong-rui Chen🇩🇪 · Chuang Huang🇩🇪 · Wei-jie Fu🇨🇳
A QCD-assisted relaxation dynamic model for the critical mode of the critical end point (CEP) in the QCD phase diagram is developed, which allows us to investigate the critical slowing down effect quantitatively in the QCD phase diagram, especially in the proximity of the CEP, without any phenomenological parameters. The relaxation time from nonequilibrium to equilibrium in the QCD phase diagram is extracted from the Langevin simulations of the QCD-assisted relaxation dynamic model. It is found that in a narrow region along the phase boundary radiated from the CEP, the relaxation time is enhanced significantly. Outside this narrow region, the relaxation time drops drastically, which implies that the dynamic critical region is small in the QCD phase diagram. We also find that the effects of critical slowing down are mild on the chemical freeze-out curves.
Comments:
7+12 pages, 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2512.03614 [pdf]
PRD(2026)·8 citations
07
[Submitted on 3 Dec 2025] (cross-list from hep-ph)
Kinetic Mixing and Axial Charges in the Parity-Doublet Model
Christian Kummer🇩🇪 · Stefan Leupold🇸🇪 · Lorenz von Smekal🇩🇪
The standard parity doublet model with its mass-mixing mechanism fails to describe the axial charge $g_{A}$ of the nucleon. While $g_{A} = 1$ in the original Gell-Mann--Levy model, which reproduces the Adler-Bell-Jackiw anomaly of QCD, in the presence of a chirally invariant baryon mass the mass mixing leads to $g_{A} < 1$ whereas phenomenologically it is about 1.28. We propose to remedy this problem by introducing kinetic-mixing terms corresponding to meson-baryon derivative couplings, similar in spirit to the two-mixing-angle scenario of the $η$ - $η^{'}$ mixing. This extended parity doublet model contains five parameters in the effective baryonic Lagrangian. Three of them can be determined by using the empirical results for the axial charge of the nucleon together with the masses of the nucleon and its parity partner, the $N^{*} (1535)$ resonance. We discuss various options how to determine the remaining parameters, touching upon the mass of both parity partners if the chiral condensate is put to zero; the mass of the nucleon in the chiral limit; and the values of meson-baryon coupling constants related to the decays of the resonance to pion-nucleon and sigma-nucleon.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2512.03894 [pdf]
PRD(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

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

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

Impact of octupole deformation on the nuclear electromagnetic response

Generalized Beth--Uhlenbeck entropy formula from the Φ−derivable approach

Effective Field Theory Perspective On King Non-linearity

Real-time evolution of critical modes in the QCD phase diagram

Kinetic Mixing and Axial Charges in the Parity-Doublet Model

Affiliations

Generalized Beth--Uhlenbeck entropy formula from the $Φ -$ derivable approach