Nuclear Theory·nucl-th

Monday·May 18, 2026

8 papers—3 primary·5 cross-listed

01
[Submitted on 14 May 2026]
Study of the shape coexistence in the 96Zr, 96Mo, 96Ru isobars
R. Budaca · P. Buganu · F. El Ouardi · A. Lahbas
Three stable isobars, $_{40}^{96}$ Zr $_{56}$ , $_{42}^{96}$ Mo $_{54}$ and $_{44}^{96}$ Ru $_{52}$ , which are in the vicinity of the harmonic oscillator proton shell closure Z=40 and the spin-orbit neutron shell closure N=50, are investigated for the presence of the shape coexistence and mixing phenomena. The ground state deformation of these isobars is extracted from the potential energy surface determined with the Covariant Density Functional Theory using a density-dependent point-coupling interaction, while the excited states are described involving the Bohr-Mottelson Hamiltonian with octic potential for both axially symmetric and $γ$ -unstable quadrupole deformations. Within the broader view of the two approaches, the obtained results clearly highlight the significant contribution of these phenomena to the structure of the states of these nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2605.15302 [pdf]
0 citations
02
[Submitted on 15 May 2026]
Microscopic derivation of the interacting boson model parameters with machine learning
Y. Obata · K. Nomura
Machine learning is applied to derive microscopically parameters of the interacting boson model for nuclear spectroscopy. A physics-guided neural network is proposed, which is trained to map the potential energy landscapes that are calculated within the nuclear density functional theory onto the bosonic parameter space. To incorporate the underlying nuclear structure information and mitigate parameter degeneracy, the network integrates a global quadrupole collectivity indicator and valence nucleon numbers as key input features. In its applications to rare-earth nuclei, by reproducing the microscopic energy landscapes without any manual parameter tuning, the trained network is shown to provide a set of the model parameters and energy spectra that reflect the nuclear structural evolution, offering a robust alternative microscopic description of nuclear collectivity.
Comments:
7 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2605.15623 [pdf]
PLB(2026)·1 citation
03
[Submitted on 15 May 2026]
Pion emission source shape in UrQMD Au+Au collisions at STAR energies
Matyas Molnar🇭🇺 · Daniel Kincses🇭🇺 · Mate Csanad🇭🇺
Femtoscopic measurements of two-pion Bose--Einstein correlations have established that particle-emitting sources in heavy-ion collisions are well described by Lévy $α$ -stable distributions, motivating systematic studies across a wide range of collision energies. In this work, we present a three-dimensional femtoscopic analysis of pion pairs in Au+Au collisions simulated with the UrQMD model for collision energies $s_{N N} = 3$ -- $27 GeV$ , taking the RHIC BES-II range of collider and fixed target experiment energies for reference. Using Lévy-type source parameterisations, we extract the pair multiplicity parameter $λ^{*}$ (related to the correlation strength $λ$ ), Lévy index $α$ , and three-dimensional radii $R_{out}$ , $R_{side}$ , and $R_{long}$ . We investigate their dependence on the transverse mass ( $m_{T}$ ) and collision energy, along with derived quantities such as the radius difference $R_{diff}^{2} = R_{out}^{2} - R_{side}^{2}$ and the ratio $R_{out} / R_{side}$ . We find that $R_{out, side, long}$ all decrease with increasing $m_{T}$ and increase with collision energy, consistent with collective expansion, $R_{long}$ showing the strongest and $R_{side}$ the weakest energy dependence. The Lévy index $α$ decreases with collision energy, with a larger $m_{T}$ -dependence towards higher energies. The $λ^{*}$ parameter is consistent with a constant close to unity in the absence of pions from long-lived resonances. These results provide a baseline for future comparisons with experimental measurements from the STAR Collaboration, contributing to constraints on the QCD phase diagram.
Comments:
11 pages, 7 figures, data file included
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2605.15717 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Study of the shape coexistence in the 96Zr, 96Mo, 96Ru isobars

Microscopic derivation of the interacting boson model parameters with machine learning

Pion emission source shape in UrQMD Au+Au collisions at STAR energies

Affiliations