Nuclear Theory·nucl-th

Monday·May 4, 2026

11 papers—4 primary·7 cross-listed

01
[Submitted on 1 May 2026]
$ρ$ mesons in finite magnetic field and finite temperature
Zhiyang Liu🇨🇳 · Min Zhou🇨🇳 · Yvming Tian🇨🇳 · Rui Zhou🇨🇳 · Guoyun Shao🇨🇳 · Shijun Mao🇨🇳
The mass spectra of $ρ$ mesons ( $ρ_{Q = \pm 1}^{s_{z} = 0, \pm 1}$ and $ρ_{Q = 0}^{s_{z} = 0, \pm 1}$ ) at finite magnetic field and temperature are studied in frame of the two-flavor Nambu-Jona-Lasinio model. Fully considering the breaking of translational invariance induced by external magnetic field, the analytical form of $ρ$ meson propagators have been derived in the Ritus scheme and Schwinger scheme, which gives the same algebraic formula. When solving the pole equation of $ρ$ meson propagators, multiple solutions of the meson mass appear due to the dimension reduction of their constituent quarks in magnetic fields. At vanishing temperature, we focus on the $ρ$ meson masses $M_{ρ}$ corresponding to the lowest value solution of the pole equation. $M_{ρ_{+}^{-}}$ , $M_{ρ_{+}^{0}}$ and $M_{ρ_{0}^{\pm}}$ increase with magnetic field. $M_{ρ_{+}^{+}}$ firstly decreases and then becomes saturated with increasing magnetic field. $M_{ρ_{0}^{0}}$ is not sensitive to magnetic field. These results are consistent with the available LQCD simulations. At finite temperature, we discuss the lowest four/five solutions of $ρ$ meson masses $M_{ρ}^{i = 0, 1, 2, 3, 4}$ . With fixed magnetic field, they decrease with temperature, and approach the mass sum of their constituent quarks at high temperature. The mass solution $M_{ρ}^{i}$ for different mesons $ρ_{+}^{0, \pm}$ and $ρ_{0}^{0, \pm}$ may become degenerate at finite magnetic field and temperature.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2605.00561 [pdf]
3 citations
02
[Submitted on 1 May 2026]
Comparative Study of Langevin and Random Walk Models for Nuclear Fission in the Overdamped Regime
A. Augustyn · T. Cap · M. Kowal · K. Pomorski
We present a comparative study of Langevin dynamics and a Metropolis random walk model applied to thermal neutron-induced fission of $^{229}$ Th, $^{235}$ U, $^{239}$ Pu, $^{245}$ Cm, $^{249}$ Cf, and $^{255}$ Fm. Both methods are implemented within an identical four-dimensional Fourier-over-Spheroid framework, using potential energy surfaces derived from the macroscopic-microscopic model. We show that the Metropolis walk corresponds to the overdamped limit of the Langevin equations and confirm this correspondence numerically by Langevin calculations performed in the strongly damped regime and with quantum corrections to the random force switched off. Under these conditions, the two approaches produce essentially identical mass distributions for the lighter actinides. Systematic deviations develop for the heavier actinides, where the Langevin dynamics yields a non-negligible symmetric fission component absent in the random walk results. We trace this difference to the kinematic structure of the Metropolis sampling and to the residual inertial dynamics retained in the Langevin framework. A parallel comparison of Langevin calculations with and without the quantum-corrected effective temperature $T^{*}$ isolates the contribution of zero-point fluctuations and suggests that their standard phenomenological treatment may overestimate their impact in certain cases. Both approaches qualitatively reproduce the asymmetric peak positions and their systematic evolution across the actinide chain, while a common quantitative limitation -- the narrowness of the predicted distributions -- points to the role of higher-dimensional deformation modes not included in the present parametrization.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2605.00586 [pdf]
0 citations
03
[Submitted on 1 May 2026]
Hyperon-nucleon interaction through the $K^{-} d \to π Λ N$ reaction
Shunsuke Yasunaga🇯🇵 · Daisuke Jido🇯🇵
The hyperon-nucleon interaction is investigated through the final-state interaction in the $K^{-} d \to π^{-} Λ p$ reaction. We focus on the $Λ N$ - $Σ N$ coupled-channel interaction, which produces characteristic structures around the $Σ N$ thresholds in the $Λ p$ invariant mass spectrum. The spin-triplet $Σ N \to Λ p$ conversion amplitude is constructed within the $K$ -matrix formalism using scattering lengths in the isospin basis. We first examine the dependence of the conversion amplitude on the $Σ N$ scattering lengths and find that the threshold structure is particularly sensitive to the sign of the real part of the $I = 1/2$ scattering length. We then calculate the $Λ p$ invariant mass spectrum of the $K^{-} d \to π^{-} Λ p$ reaction, including the contributions from the background diagrams. The resulting spectra show characteristic structures around the $Σ N$ thresholds, whose shapes depend on the choice of the interaction parameters. These results suggest that the $Λ p$ invariant mass spectrum can serve as a useful observable for constraining the $Λ N$ - $Σ N$ coupled-channel interaction.
Comments:
4 pages, 3 figures, Proceedings of the 2025 International Conference on the Structure of Baryons (Baryons 2025), 10-14 Nov. 2025, Jeju, South Korea
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2605.00727 [pdf]
J.Subatomic Part.Cosmol.(2026)·0 citations
04
[Submitted on 1 May 2026]
Two-body current and axial form factor effects in charged-current quasielastic neutrino-nucleus scattering within the NEUT event generator
T. Franco-Munoz🇧🇪 · J. McKean🇯🇵 · J. García-Marcos🇧🇪 · M. Hooft🇧🇪 · R. González-Jiménez🇪🇸 · N. Jachowicz🇧🇪 · J. M. Udías🇪🇸
We present a charged-current quasielastic neutrino-nucleus scattering model based on an unfactorized representation of the spectral function, employing relativistic momentum distributions for bound nucleons and the relativistic distorted-wave impulse approximation with an energy-dependent relativistic potential to describe the scattered nucleon. The model incorporates two-body meson-exchange currents contributing to one-particle-one-hole final states and tests several axial form factor parametrizations, including recent LQCD and MINERvA fits. It is implemented in the NEUT event generator and benchmarked against T2K and MINERvA $ν_{μ}$ - $^{12}$ C CC0 $π$ measurements. We find that two-body meson-exchange currents lead to a sizeable increase of the total cross section, arising from an enhancement of the transverse response, which is the dominant component in charged-current neutrino scattering. On the other hand, recent fits of the axial form factor predict larger values than the standard dipole form, yielding a systematic enhancement of the cross section. The LQCD+MINERvA parametrization tends to overestimate the data, while the MINERvA-only fit provides a more moderate increase. Overall, no single configuration consistently provides the best agreement with the different datasets.
Comments:
18 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2605.00756 [pdf]
PRD(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

ρ mesons in finite magnetic field and finite temperature

Comparative Study of Langevin and Random Walk Models for Nuclear Fission in the Overdamped Regime

Hyperon-nucleon interaction through the K−d→πΛN reaction

Two-body current and axial form factor effects in charged-current quasielastic neutrino-nucleus scattering within the NEUT event generator

Affiliations

$ρ$ mesons in finite magnetic field and finite temperature

Hyperon-nucleon interaction through the $K^{-} d \to π Λ N$ reaction