Nuclear Theory·nucl-th

Thursday·March 5, 2026

9 papers—5 primary·4 cross-listed

01
[Submitted on 3 Mar 2026]
Microscopic description of cluster radioactivity fission valleys along isotopic and isotonic chains
M. Warda · A. Zdeb · R. Rodríguez-Guzmán
Cluster radioactivity has been successfully described as a super-asymmetric fission mode within the microscopic self-consistent Gogny Hartree-Fock-Bogoliubov approximation [Phys. Rev. C 84, 044608 (2011)]. For nuclei preserving the neutron-to-proton $N / Z$ ratio of the doubly magic $^{208}$ Pb, a cluster radioactivity fission valley has been identified. Such a valley can also be found both in actinides and super-heavy nuclei. In this paper, chains of isotopes and isotones are examined to determine the limits of existence of the cluster radioactivity fission mode. It is shown that the super-asymmetric valley can be found in a wide range of the nuclear chart. Nevertheless, the valley flattens more and more when diverging from the isospin asymmetry of $^{208}$ Pb. For neutron-deficient nuclei with $N / Z <$ 1.41, it is found that the valley diminishes before reaching the scission point, and cluster radioactivity can not be observed.
Comments:
13 figures, accepted to publish in PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2603.03519 [pdf]
PRC(2026)·2 citations
02
[Submitted on 4 Mar 2026]
Empirical Universal Scaling of Neutron-Skin Curvature Across the Nuclear Chart
Brent Baker
Neutron skins encode essential information about nuclear geometry, surface structure, and isovector response, yet a compact description across the nuclear chart remains elusive. We present an empirical analysis of neutron-excess surface systematics using a mass-normalized, charge-radius-derived proxy ("neutron-skin curvature") built from evaluated experimental charge radii. By normalizing radii to the reduced Compton length $r_{B} = ℏ/ (m c)$ , we form a dimensionless curvature ratio that enables comparison across isotopic chains of widely varying mass. When expressed versus normalized neutron excess, data for more than 800 nuclei spanning 88 elements collapse onto a single empirical curve without element-specific rescaling or interaction-model tuning; the curve is used only as a fixed baseline for residual analysis. The collapse accounts for approximately 88% of the variance and is substantially tighter than droplet-style baselines fit to the same dataset. Residuals show structured deviations: three finite-size regimes (skin formation, relaxation toward bulk geometry, and saturation) and a distinct few-body domain for very light nuclei ( $Z \leq 4$ ). Stratifying residuals by periodic-table families reveals tighter submanifolds for several groups, suggesting additional geometric constraints layered on the global trend. These results are obtained directly from evaluated experimental data and physical constants, without introducing new interaction terms, and motivate further study of geometric correlations with other nuclear and atomic observables.
Comments:
42 pages, 14 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2603.03698 [pdf]
0 citations
03
[Submitted on 4 Mar 2026]
From Orthogonalizing Pseudopotential to the Feshbach-Schur Projection
M. M. Nishonov
The orthogonalizing pseudopotential (OPP) is the standard tool for suppressing Pauli-forbidden states in cluster models of light nuclei. Here it is shown to be the singular $λ \to \infty$ limit of a Feshbach--Schur projection. The auxiliary coupling $λ$ is eliminated in closed form: the result is a Schur-complement operator identity for a general multi-rank separable interaction, written in both momentum and configuration space. The projected equations contain no large parameter. The identity is verified in three-body Faddeev calculations of the $^{6}$ He and $^{6}$ Li ground states with separable two-body input. The binding energies at finite $λ$ follow the predicted $1/ λ$ behavior over five orders of magnitude of $λ$ and converge to the result of the closed projected equations. The $α N$ $D$ -wave contribution, $7$ ~keV in $^{6}$ He and $90$ ~keV in $^{6}$ Li, does not depend on $λ$ and does not affect the projection.
Comments:
20 pages. v3: introduction and discussion shortened
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2603.03842 [pdf]
0 citations
04
[Submitted on 4 Mar 2026]
Nuclear matter properties and neutron star structures from an extended linear sigma model
Yao Ma🇨🇳
The properties of nuclear matter and the structures of neutron stars are analyzed with a baryonic extended linear sigma model in mean-field approximation, where the masses of baryons and mesons are generated via the spontaneous chiral symmetry breaking. The couplings between the iso-scalar scalar meson and nucleons, $g_{σ N N}$ , the iso-vector scalar meson and nucleons, $g_{a_{0} N N}$ , and the four-vector meson couplings play an important role in the properties of nuclear matter and neutron stars. The introduction of the $δ$ meson leads to a plateau structure of the symmetry energy, $E_{sym} (n)$ , at intermediate densities, which is crucial to the consistency of neutron skin thickness of $^{208}$ Pb and the tidal deformability of a canonical neutron star. The explicit chiral symmetry breaking term is then introduced with a constant background field, $ξ$ , which can be related to the current quark mass and thus the pion-nucleon sigma term, $σ_{π N}$ . A negative $σ_{π N}$ leads to a stiffer EOS of neutron star matter and thus a larger maximum mass of neutron stars, but the value of $σ_{π N}$ needed to satisfy the astrophysical constraints is negative, not positive as the vacuum value. The study may provide insights into the running behaviors of the parameters in the low-energy effective model to give the density-dependent description for the EOS of neutron star matter.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2603.03849 [pdf]
J.Subatomic Part.Cosmol.(2026)·0 citations
05
[Submitted on 4 Mar 2026]
Similarity renormalization group for nuclear forces
Matthias Heinz
Renormalization group methods generate low-resolution Hamiltonians that are more diagonal, with reduced coupling between low- and high-energy states, and thus easier to solve. This chapter reviews the similarity renormalization group for nuclear Hamiltonians, which is a popular method for generating low-resolution nuclear forces. It presents the similarity renormalization group flow equations, analyzes how the similarity renormalization group drives the Hamiltonian towards the diagonal, and studies the effect of induced many-body interactions. It concludes by highlighting the progress in first-principles calculations of nuclei driven by low-resolution nuclear Hamiltonians.
Comments:
15 pages, 6 figures, invited pedagogical chapter submitted to Encyclopedia of Nuclear Physics (Elsevier, 1st Edition), accepted version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2603.04311 [pdf]
1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Microscopic description of cluster radioactivity fission valleys along isotopic and isotonic chains

Empirical Universal Scaling of Neutron-Skin Curvature Across the Nuclear Chart

From Orthogonalizing Pseudopotential to the Feshbach-Schur Projection

Nuclear matter properties and neutron star structures from an extended linear sigma model

Similarity renormalization group for nuclear forces

Affiliations