Nuclear Theory·nucl-th

Thursday·October 2, 2025

10 papers—6 primary·4 cross-listed

01
Relativistic hydrodynamics with spinodal decomposition
Joseph Kapusta🇺🇸 · Mayank Singh🇺🇸 · Thomas Welle🇺🇸
We introduce the equations of relativistic hydrodynamics that incorporate phase separation via spinodal decomposition. These equations consider surface effects between the two phases and are applicable for simulating intermediate-energy heavy-ion collisions and binary neutron star mergers, where a first-order phase transition is expected. We solve these equations in the context of Bjorken flow, which offers the relevant geometric framework for ion collisions.
nucl-thhep-phEPJ Web Conf.(2026)·0 citations
02
Statistical properties of neutron-induced reaction cross sections using random-matrix approach
K. Fujio · T. Kawano · A. E. Lovell · D. Neudecker
We investigate the statistical properties of neutron-induced nuclear reactions on $^{238}$ U using the GOE- $S$ -matrix model, in which the Gaussian Orthogonal Ensemble (GOE) is embedded into the scattering ( $S$ ) matrix. The GOE- $S$ -matrix model does not require any experimental values of the average level spacing $D$ and average decay width $Γ$ with their statistical distributions, but the model is fully characterized by the channel transmission coefficients used in the Hauser-Feshbach theory. We demonstrate that the obtained compound nucleus decay width distribution resembles the $χ$ -squared distribution with the degree of freedom greater than unity. This approach enables us to generate fluctuating cross sections while preserving requisite unitarity and accounting for interference between resonances. By comparing the calculated cross section distribution with that from $R$ -matrix theory, we demonstrate a smooth transition from the resolved resonance region to the continuum region.
nucl-thPRC(2025)·1 citation
03
Next highest weight and other lower $S U (3)$ irreducible representations with proxy- $S U (4)$ symmetry for nuclei with $32 \leq \mbox Z, N \leq 46$
V.K.B. Kota
In the applications of proxy-SU(3) model in the context of determining $(β, γ)$ values for nuclei across the periodic table, for understanding the preponderance of triaxial shapes in nuclei with $Z \geq 30$ , it is seen that one needs not only the highest weight (hw) or leading $S U (3)$ irreducible representation (irrep) $(λ_{H}, μ_{H})$ but also the lower $S U (3)$ irreps $(λ, μ)$ such that $2 λ + μ = 2 λ_{H} + μ_{H} - 3 r$ with $r = 0, 1$ and $2$ [Bonatsos et al., Symmetry {\bf 16}, 1625 (2024)]. These give the next highest weight (nhw) irrep, next-to-next highest irrep (nnhw) and so on. Recently, it is shown that for nuclei with $32 \leq \mbox Z, N \leq 46$ , there will be not only proxy- $S U (3)$ but also proxy- $S U (4)$ symmetry [Kota and Sahu, Physica Scripta {\bf 99}, 065306 (2024)]. Following these developments, presented in this paper are the $S U (3)$ irreps $(λ, μ)$ with $2 λ + μ = 2 λ_{H} + μ_{H} - 3 r$ , $r = 0, 1, 2$ for various isotopes of Ge, Se, Kr, Sr, Zr, Mo, Ru and Pd (with $32 \leq \mbox N \leq 46$ ) assuming good proxy- $S U (4)$ symmetry. A simple method for obtaining the SU(3) irreps is described and applied. The tabulations for proxy- $S U (3)$ irreps provided in this paper will be useful in further investigations of triaxial shapes in these nuclei.
nucl-th1 citation
04
Bulk and spectroscopic nuclear properties within an ab initio renormalized random-phase approximation framework
Radek Folprecht · František Knapp · Giovanni De Gregorio · Riccardo Mancino · Petr Veselý · Nicola Lo Iudice
A modern chiral potential incorporating the three-body force is adopted to investigate bulk properties, spectra, and nuclear responses of closed-(sub)shell nuclei throughout the nuclear chart within a particle-hole (p-h) renormalized random-phase approximation (RRPA) scheme using a Hartree- Fock (HF) single-particle basis. Our analysis shows that all instabilities induced by the quasiboson approximation (QBA) underlying RPA are removed and an overall better consistency with the experiments is achieved for all observables of the investigated nuclei. The residual discrepancies point out the need of going beyond the p-h space.
nucl-thphysics.comp-phPRC(2026)·1 citation
05
A new effective theory for stochastic relativistic hydrodynamics
Nicki Mullins🇺🇸 · Mauricio Hippert🇧🇷 · Jorge Noronha🇺🇸
Thermal fluctuations are a fundamental feature of dissipative systems that are essential for understanding physics near the expected critical point of QCD and in small systems. When such fluctuations are modeled naively in relativistic systems, strange features can appear such as negative self-correlation functions. We construct an effective theory for nonlinear stochastic relativistic hydrodynamics that ensure a well-posed mathematical formulation. Using Crooks fluctuation theorem, we derive a symmetry of the effective action that incorporates fluctuations through a suitable free energy functional. For divergence type theories, the action can then be fully specified using a single vector generating current. The equations of motion obtained using this procedure are guaranteed to be flux conservative and symmetric hyperbolic when the dynamics is causal. This ensures that these equations are well-posed (for suitable initial data) and are in a form that can easily be simulated, including with Metropolis techniques.
nucl-thEPJ Web Conf.(2026)·0 citations
06
Properties of Neutron Stars with Hyperons within a Relativistic Metamodel
Prasanta Char🇪🇸 · Chiranjib Mondal🇧🇪 · Timothé Alezraa🇫🇷 · Francesca Gulminelli🇫🇷 · Micaela Oertel🇫🇷
In this work, we study the effects of $Λ$ -hyperons on neutron star properties employing a metamodel framework for the equation of state (EoS). Different choices for defining the hyperonic couplings with different levels of parametric freedom are discussed. In all models, the predicted NS maximum masses are reduced compared with the purely nucleonic composition as expected. In the case of relating hyperonic couplings via $S U (6)$ -symmetry arguments to the nucleonic ones, we find that NS radii for intermediate mass stars are shifted to higher values compared with purely nucleonic stars, in agreement with the existing literature. However, allowing for more freedom for the hyperonic couplings, the effect is strongly reduced, and the distributions in the NS mass-radius plane of models with and without hyperons become very close. We have also investigated how different nucleonic density functionals influence the hyperon matter composition and neutron star properties.
nucl-thastro-ph.HE3 citations
07
Chiral effects and Joule heating in hot and dense matter
Srimoyee Sen🇺🇸 · Varun Vaidya🇺🇸
Initial states of dense matter with nonzero electron chiral imbalance could potentially give rise to strong magnetic fields through chiral plasma instability. Previous work indicated that unless chiral chemical potential is as large as the electron vector chemical potential, the growth of magnetic fields due to the instability is washed out by chirality flipping rate enabled by electron mass. We re-examine this claim in a broader range of parameters and find that at higher temperatures the hierarchy is reversed supporting a growing magnetic field for an initial electron chiral chemical potential much smaller than the electron vector chemical potential. Further, we identify a qualitatively new effect relevant for magnetized hot and dense medium where chiral magnetic effect (CME) sourced by density fluctuation acts as a powerful source of Joule heating. Remarkably, even modest chiral chemical potentials (keV) in such environment can deposit energy densities set by the QCD scale in a relatively short time of the order of a few milliseconds or seconds. We speculate how this mechanism makes CME-driven Joule heating a potentially critical ingredient in the dynamics of turbulent density fluctuation of supernovae and neutron star mergers.
↳ hep-phastro-ph.HEnucl-thPRD(2026)·2 citations
08
Scaling properties of nuclear parton distributions in short-range-correlation motivated two-component parametrization
Petja Paakkinen🇫🇮
We provide some critical remarks on the recently proposed two-component parametrization of nuclear parton distribution functions, which was motivated by the apparent correlation between the nuclear modifications of structure functions and nucleon-nucleon short-range correlation phenomena. This parametrization, we show, is invariant under a rescaling transformation of the involved abundance coefficients, which means that the global normalization of these coefficients cannot be meaningfully determined in a fit, and only their ratios should be studied for finding evidence of short-range-correlation type behavior at parton level. As we show, however, the current constraints for the nuclear-mass dependence of these coefficients allow also for interpretations different from short-range correlations. Nevertheless, this two-component parametrization exhibits a similar scaling relation for DIS structure functions as demonstrated in earlier works, and, as we demonstrate, yields testable predictions for structure-function and hard-process cross-section ratios. We also note on the non-trivial isospin dependence of the short-range-correlation motivated parametrization, which under proton-neutron pair dominance assumption can lead to charge-symmetry-violation resembling terms.
↳ hep-phnucl-thPRD(2026)·4 citations
09
Gluon Condensation as a Unifying Mechanism for Special Spectra of Cosmic Gamma Rays and Low-Momentum Pion Enhancement at the Large Hadron Collider
Wei Zhu🇨🇳 · Jianhong Ruan🇨🇳 · Xurong Chen🇨🇳 · Yuchen Tang🇨🇳
Decoding the internal structure of the proton is a fundamental challenge in physics. Historically, any new discovery about the proton has fuelled advances in several scientific fields. We have reported that gluons inside the proton accumulate near the critical momentum due to chaotic phenomena, forming gluon condensation. Surprisingly, the pion distribution predicted by this gluon distribution for the production of high-energy proton collisions could answer two puzzles in astronomy and high-energy physics. We find that during ultrahigh-energy cosmic ray collisions, gluon condensation may abruptly produce a large number of low-momentum pions, whose electromagnetic decays have the typical breakout properties appearing in various cosmic gamma-ray spectra. On the other hand, the Large Hadron Collider (LHC), which is well below the cosmic ray energy scale, also shows weak but recognisable signs of gluon condensation, which had been mistaken for BEC pions. The connection between these two phenomena, which occur at different scales in the Universe, supports the existence of a new structure within the proton-gluon condensation.
↳ hep-phastro-ph.HEnlin.CDnucl-thSymmetry(2025)·0 citations
10
Nonperturbative fluctuation effects of charged bosonic fields: A quark-diquark model study at nonzero density
Jonas Stoll🇩🇪 · Niklas Zorbach🇩🇪 · Jens Braun🇩🇪
We study the renormalization group flow of the scale-dependent effective potential of a quark-diquark model with full field dependence at nonzero chemical potential. This includes a discussion of approximations in relation to complex bosonic fields and the Silver-Blaze property. The resulting flow equation for the scale-dependent effective potential can in principle be solved down to the infrared limit. For our quark-diquark model, which may serve as a low-energy model for dense strong-interaction matter, we find that a competition between the Bardeen-Cooper-Schrieffer singularity and bosonic fluctuations can trigger a first-order phase transition at low temperatures that turns into a second-order phase transition at a tricritical point as the temperature increases.
↳ hep-phcond-mat.supr-connucl-th7 citations

Affiliations

first authorsco-authorsvia INSPIRE