Nuclear Theory·nucl-th

Monday·January 26, 2026

10 papers—6 primary·4 cross-listed

01
[Submitted on 23 Jan 2026]
Analysis of $M 1$ capture in the $α (d, γ)^{6}$ Li reaction
Ergash M. Tursunov · Daniel Baye
An effective operator is exactly equivalent to the long-wavelength form of the $M 1$ operator in transition matrix elements. It allows us to analytically and numerically analyze the $M 1$ contribution to the $α (d, γ)^{6}$ Li reaction. Isoscalar $M 1$ transitions from an initial $S$ wave are shown to be forbidden in radiative capture reactions when distortion is neglected in the initial state. A calculation in a three-body model with proton, neutron, and a structureless $α$ interacting through effective forces leads to a negligible $M 1$ $S$ -factor at small energies. The dominant $M 1$ contribution comes from transitions from an initial $S$ wave to isospin 1 components of the $^{6}$ Li ground state. It is suggested that using this effective $M 1$ operator in other models should clarify the origin of large discrepancies between $M 1$ $S$ -factors appearing in the literature.
Comments:
18 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Experiment (nucl-ex)
arXiv:
2601.16551 [pdf]
PRC(2026)·0 citations
02
[Submitted on 23 Jan 2026]
Nuclear molecule of heavy nuclei
T. M. Shneidman · R. G. Nazmitdinov
The model of a nuclear molecule that composed of two heavy nuclei is proposed. To this aim the Hamiltonian of a dinuclear system is derived and diagonalized in the basis of bipolar spherical functions. Analytical expressions, describing excitations of highly deformed states of a nuclear molecule, are obtained. A remarkable agreement between numerical and analytical results is demonstrated at the description of roto-vibrational excitations in $^{240}$ Pu at low energies. We provide the prediction for the spectrum of hyperdeformed states of the nucleus $^{232}$ Th, considering it as a nuclear molecule that consists of $^{132}$ Sn+ $^{100}$ Zr nuclei. The angular distribution of fission fragments for the nucleus $^{240}$ Pu have been analyzed as well and compared with available experimental data.
Comments:
49 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2601.16600 [pdf]
J.Phys.A(2026)·0 citations
03
[Submitted on 23 Jan 2026]
Non-Equilibrium Trace Anomaly And Bulk Viscosity in Heavy Ion Collisions From Kinetic Theory
Krishanu Sengupta · Reghukrishnan Gangadharan · Victor Roy
We investigate the far-from-equilibrium dynamics and transport properties of a relativistic massive gas obeying Maxwell-Boltzmann (MB), Bose-Einstein (BE), and Fermi-Dirac (FD) statistics undergoing a boost-invariant Bjorken expansion. We solve the relativistic Boltzmann equation in the relaxation-time approximation (RTA) using the method of moments. We focus on the time evolution of the trace of the energy-momentum tensor $Θ^{μ}_{μ}$ and the bulk viscous pressure $Π$ , which are key diagnostics of conformal-symmetry breaking in the rapidly evolving fireball created in heavy-ion collisions. We find that the non-equilibrium quantity $Θ^{μ}_{μ} / T^{4}$ exhibits a non-monotonic time dependence, with a local maximum at early times and a pronounced dip around the characteristic relaxation time scale $τ_{R}$ . We further show that the scaled bulk pressure $Π/ P_{0}$ , where $P_{0}$ denotes the isotropic equilibrium pressure, depends sensitively on the particle statistics. In addition, increasing the initial chemical potential enhances the magnitudes of both $Π$ and $Θ^{μ}_{μ} / T^{4}$ . Finally, by initializing the system with random non-equilibrium configurations, we demonstrate that the evolution of the scaled bulk pressure and the pressure anisotropy converges to a common late-time solution.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2601.16625 [pdf]
1 citation
04
[Submitted on 23 Jan 2026]
Tribute to Tullio Bressani, Bogdan Povh and Toshimitsu Yamazaki
Avraham Gal
In this HYP2025 talk I pay tribute to Tullio Bressani (1940-2024), Bogdan Povh (1932-2024) and Toshimitsu Yamazaki (1934-2025), all of whom made lasting contributions to shaping up Strangeness Nuclear Physics. Yoshinori Akaishi's (1941-2025) record is also noted.
Comments:
Plenary talk at HYP2025, Tokyo, Sept.-Oct. 2025, to be published in JPS Conf Proc
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); History and Philosophy of Physics (physics.hist-ph)
arXiv:
2601.16678 [pdf]
0 citations
05
[Submitted on 23 Jan 2026]
Compatibility of recent $S = - 2$ emulsion events
Avraham Gal🇮🇱
We question the compatibility of recent $S = - 2$ hypernuclear assignments of J-PARC E07 $Ξ^{-}$ -capture emulsion events with assignments deduced from other experiments.
Comments:
Orally presented contribution at HYP2025, Tokyo, Sept.-Oct. 2025, to be published in JPS Conf Proc
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2601.16692 [pdf]
0 citations
06
[Submitted on 23 Jan 2026]
Universal relation between dipole polarizability of finite nuclei and neutron-star compactness
P.S. Koliogiannis · T. Ghosh · E. Yuksel · N. Paar
The nuclear equation of state, which determines the structure and properties of neutron stars, remains subject to substantial theoretical uncertainties, leading to model dependence in predicted observables. Universal relations have emerged as a powerful tool to mitigate this dependence by linking neutron star observables in a framework-independent manner. In this work, we introduce a new universal relation that \emph{bridges} finite nuclei and neutron stars through the dimensionless quantity $ζ = β_{1.4} L ~^{- 1}$ , which couples the compactness of a $1.4 M_{⊙}$ neutron star to the slope of the nuclear symmetry energy at saturation. The relation is examined under a broad set of relativistic energy density functionals with point-coupling and meson-exchange interactions, as well as non-relativistic Skyrme functionals. We demonstrate that $ζ$ exhibits a strong exponential correlation with the electric dipole polarizability $α_{D}$ in finite nuclei across all considered equations of state. By exploiting experimental $α_{D}$ data for selected neutron-rich nuclei, we constrain $ζ$ and translate these constraints into equation-of-state independent bounds on the neutron star radius $R_{1.4}$ and the symmetry-energy slope $L$ , providing insights into the properties of neutron star matter.
Comments:
v1: 10 pages, 4 figures, 4 tables; v2: 10 pages, 4 figures, 4 tables; matched published version in Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2601.16894 [pdf]
PRC(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Analysis of M1 capture in the α(d,γ)6Li reaction

Nuclear molecule of heavy nuclei

Non-Equilibrium Trace Anomaly And Bulk Viscosity in Heavy Ion Collisions From Kinetic Theory

Tribute to Tullio Bressani, Bogdan Povh and Toshimitsu Yamazaki

Compatibility of recent S=−2 emulsion events

Universal relation between dipole polarizability of finite nuclei and neutron-star compactness

Affiliations

Analysis of $M 1$ capture in the $α (d, γ)^{6}$ Li reaction

Compatibility of recent $S = - 2$ emulsion events