Nuclear Theory·nucl-th

Thursday·March 5, 2026

9 papers—5 primary·4 cross-listed

01
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.
nucl-thPRC(2026)·2 citations
02
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.
nucl-th0 citations
03
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.
nucl-th0 citations
04
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.
nucl-thJ.Subatomic Part.Cosmol.(2026)·0 citations
05
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.
nucl-th1 citation
06
Inverse Excitation Hierarchy in Doubly-Heavy Tetraquarks within the Diquark Model
Maximilian Weber🇯🇵 · Daiki Suenaga🇯🇵 · Masayasu Harada🇯🇵
We investigate the $T_{cc}$ tetraquark, treating it as a bound state of a heavy diquark and a light antidiquark. Using the Silvestre-Brac potential and solving the Schrödinger equation via the Gaussian Expansion Method, we find that the excitation energy between the heavy diquark and light antidiquark is unexpectedly larger than that between the two light anti-quarks within the anti-diquark -- contrary to the naive expectation where the former is smaller than the latter. We trace this inversion of the mass hierarchy to the centrifugal force acting on the light degree of freedom. Applying the same framework to other systems ( $T_{bb}, Λ_{b}, Λ_{c}$ ) yields qualitatively identical behavior, demonstrating the robustness of the mechanism. These results provide new insights into diquark dynamics and the mass structure of exotic hadrons.
↳ hep-phnucl-thPRD(2026)·0 citations
07
Lattice extraction of the Collins-Soper kernel using the auxiliary field representation of the Wilson line
Anthony Francis🇹🇼 · C.-J. David Lin🇹🇼 · Wayne Morris🇹🇼 · Yong Zhao🇺🇸
The Collins-Soper (CS) kernel may be obtained through the TMD soft function by formulating the Wilson line in terms of 1-dimensional auxiliary fermion fields on the lattice. Our computation takes place in the region of the lattice that corresponds to the "spacelike" region in Minkowski space, i.e., Collins' scheme. We explore two methods for obtaining the CS kernel. The "ratio method"; which would allow us to obtain the soft function as well as the CS kernel. And the "double ratio"; which allows us to achieve a high degree of statistical precision, but only produces the CS kernel. The matching of our result to Minkowski space is achieved through the mapping of the complex auxiliary field directional vector to the Wilson line rapidity. We present a preliminary extraction of the CS kernel using the "double ratio", and discuss the methodology employed.
↳ hep-lathep-phhep-thnucl-th0 citations
08
Topological observables and domain wall tension from finite temperature chiral perturbation theory
Zhen-Yan Lu🇨🇳 · Quan Tang🇨🇳 · Shu-Peng Wang🇨🇳 · Yang Huang🇨🇳 · Zhen Zhang🇨🇳 · Bonan Zhang🇨🇳
Within the framework of SU(2) chiral perturbation theory, we derive the general solution of the QCD $θ$ -vacuum for an arbitrary vacuum phase, explicitly incorporating isospin-breaking effects from the light quark mass difference, and compute the temperature dependence of the topological susceptibility, higher-order cumulants, and the domain wall tension up to next-to-leading order. We find that the topological susceptibility agrees with lattice data at low temperatures but deviates at higher temperatures as expected from the breakdown of the chiral expansion; moreover, we demonstrate that the normalized fourth-order cumulant and the domain wall tension decrease monotonically with increasing temperature, while the normalized sixth-order cumulant exhibits the opposite behavior. These results extend earlier analyses by showing how isospin breaking reshapes the full hierarchy of topological charge cumulants and the dynamics of $θ$ -vacuum domain walls, thereby offering new theoretical input on the $θ$ -vacuum properties, which are relevant for axion-related effective theories in hot QCD matter.
↳ hep-phhep-lathep-thnucl-thPRD(2026)·2 citations
09
Quantum Kinetic Theory for Quantum Chromodynamics
Shu Lin🇨🇳
We develop a quantum kinetic theory for QCD, which incorporates all leading order collision terms. At lowest order in gradient expansion, it reproduces the spin-averaged Boltzmann equation with both elastic and inelastic collisions. At next order in gradient expansion, the solution to the quantum kinetic equations give spin polarization of on-shell quarks and gluons in quark-gluon plasma when the gradients are of hydrodynamic ones. A power counting in the coupling shows the spin polarization behaves differently in vortical and non-vortical gradients: the former is free of collisional contribution to leading order, while the latter contains a collisional contribution at parametrically the same order as the free theory counterpart. We also find the inelastic collision in a spin basis provides a possible mechanism for conversion between spin and orbital angular momentum.
↳ hep-phnucl-th1 citation

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first authorsco-authorsvia INSPIRE