Nuclear Theory·nucl-th

Tuesday·July 15, 2025

17 papers—6 primary·11 cross-listed

01
Exact solutions of the nuclear shell-model secular problem: Discrete Non-Orthogonal Shell Model within a Variation After Projection approach
Duy Duc Dao🇫🇷 · Frédéric Nowacki🇫🇷
We investigate the capacity of non-orthogonal many-body expansions in the resolution of the nuclear shell-model secular problem. Exact shell-model solutions are obtained within the variational principle using non-orthogonal Slater determinants as the variational ansatz. These results numerically prove the realization of the Broeckhove-Deumens theorem on the existence of a discrete set of non-orthogonal wavefunctions that exactly span the full shell-model space for low-lying states of interest. With the angular-momentum variation after projection, pairing correlations are shown to be fully captured by Slater determinants as exemplified in the backbending phenomenon occurred in $^{48}$ Cr. The resulting discrete non-orthogonal shell model developed in such variation after projection method is further examined in the case of $^{78}$ Ni, an exotic doubly magic nucleus at the edge of currently feasible diagonalization limits. Its ground state binding energy is shown to converge to a lower value than the largest large-scale shell-model diagonalization ever done by the conventional tridiagonal Lanczos method, revealing an outstanding performance of non-orthogonal Slater determinantal wavefunctions to describe the eigensolutions of shell-model Hamiltonians.
nucl-thPRC(2026)·5 citations
02
Bayesian approach for many-body uncertainties in nuclear structure: Many-body perturbation theory for finite nuclei
Isak Svensson · Alexander Tichai · Kai Hebeler · Achim Schwenk
A comprehensive assessment of theoretical uncertainties defines an important frontier in nuclear structure research. Ideally, theory predictions include uncertainty estimates that take into account truncation effects from both the interactions and the many-body expansion. While the uncertainties from the expansion of the interactions within effective field theories have been studied systematically using Bayesian methods, many-body truncations are usually addressed by expert assessment. In this work we use a Bayesian framework to study many-body uncertainties within many-body perturbation theory applied to finite nuclei. Our framework is applied to a broad range of nuclei across the nuclear chart calculated from two- and three-nucleon interactions based on chiral effective field theory. These developments represent a step towards a more complete and systematic quantification of uncertainties in \emph{ab initio} calculations of nuclei.
nucl-thPRC(2026)·11 citations
03
Pseudo-gauge invariant non-equilibrium density operator
F. Becattini🇮🇹 · C. Hoyos🇪🇸
We obtain a form of the local thermodynamic equilibrium density operator which is invariant under pseudo-gauge transformations of the stress-energy and the spin tensors. This operator is an excellent candidate to describe the dynamics of a system which is assumed to achieve local equilibrium from a pseudo-gauge invariant quantum state, a situation which is believed to occur, for instance, in nuclear collisions at very high energy. As a consequence of pseudo-gauge invariance, the ambiguity affecting the predictions of mean values of observables from a local equilibrium state can be removed.
nucl-thcond-mat.stat-mechhep-thPRL(2026)·13 citations
04
Light and heavy $Λ$ hyperclusters in nuclear matter with relativistic-mean-field models
Cheng-Jun Xia🇨🇳 · Yu-Ting Rong🇨🇳 · Ting-Ting Sun🇨🇳
In the framework of relativistic-mean-field (RMF) models, we investigate the properties of light and heavy $Λ$ hyperclusters emersed in nuclear matter at various densities $n_{gas}$ and proton fractions $Y_{p}$ . In particular, the (hyper)clusters are fixed by solving the Dirac equations imposing the Dirichlet-Neumann boundary condition, while the nuclear matter take constant densities and is treated with Thomas-Fermi approximation. The binding energies of (hyper)clusters decrease with the density of nuclear matter $n_{gas}$ , which eventually become unbound and melt in the presence of nuclear medium, i.e., Mott transition. For light clusters with proton numbers $N_{p} < 4$ , with the addition of $Λ$ hyperons, the binding energies per baryon for $Λ$ hyperclusters become smaller and decrease faster with $n_{gas}$ due to the weaker $N$ - $Λ$ attraction. For heavy clusters with $N_{p} \geq 4$ , on the contrary, the addition of $Λ$ hyperons increases the stability of (hyper)clusters so that the Mott transition density becomes larger as nucleons occupying higher energy states while $Λ$ hyperons remain in the $1 s_{1/2}$ orbital. The isovector effects on (hyper)clusters in nuclear medium are also identified, where the binding energies for (hyper)clusters with $N_{p} > N_{n}$ ( $N_{p} < N_{n}$ ) increase (decrease) with $Y_{p}$ . For those predicted by nonlinear relativistic density functionals, light (hyper)clusters are destabilized drastically as $n_{gas}$ increases, while the binding energies of heavier (hyper)clusters vary smoothly with $n_{gas}$ . The binding energy shifts of various (hyper)clusters due to the impact of nuclear medium are fitted to an analytical formula, which could be employed to examine the evolutions of (hyper)clusters in both heavy-ion collisions and neutron stars.
nucl-thPRC(2025)·2 citations
05
Proton radioactivity in deformed nuclei with microscopic optical potential: A novel angular-dependent emission mechanism in the nanosecond-lived $^{149}$ Lu
Yin Fan · Sibo Wang · Xiao-Hua Li · Haozhao Liang
We present a theoretical description of proton radioactivity in 149Lu, the most oblate deformed proton emitter known, by combining a deformed microscopic optical potential derived from ab initio nuclear matter calculations with the Wentzel-Kramers-Brillouin penetration probabilities and the assault frequency of the emitted proton estimated through a new harmonic-oscillator-inspired scheme. We predict a novel angular-dependent phenomenon unprecedented in spherical proton emitters: the disappearance of classically allowed regions at small polar angles $(θ \leq 2 1^{\circ})$ . Our framework yields a half-life $T_{1/2} = 46 7_{- 108}^{+ 143}$ ns for 149Lu, in excellent agreement within uncertainties with the experimental value $45 0_{- 100}^{+ 170}$ ns. Deformation analysis rigorously excludes configurations with $∣ β_{2} ∣ \geq 0.32$ . Extensions to 150, 151Lu and their isomers also achieve excellent agreement with experimental half-life data. We further predict 148Lu as another highly oblate $(β_{2} = - 0.166)$ proton emitter with a half-life $T_{1/2} = 4.42$ ns. This work validates deformed microscopic optical potentials as a robust predictive tool for drip-line proton emitters and provides quantitative evidence for deformation effects in exotic decays.
nucl-thnucl-exPRC(2026)·2 citations
06
Composition of scalar mesons and their effects on nuclear matter properties in an extended linear sigma model
Yao Ma🇨🇳 · Yong-Liang Ma🇨🇳
It has been argued that the iso-scalar and iso-vector mesons play significant roles in nuclear matter and neutron star structures. We improve the extended linear sigma model with baryons, proposed in our previous work, by introducing the flavor structures constructed from antisymmetric tensors of chiral representations to study these physics. The parameter space of this model is refined with well-reproduced nuclear matter properties at saturation density by the lowest order Lagrangian, ensuring consistency with vacuum results, such as $f_{π} \approx 134 MeV$ . The anticipated plateau-like behaviors of the symmetry energy are predicted at intermediate densities, which is crucial for the consistency of GW170817 and the neutron skin thickness of $Pb^{208}$ . Subsequently, neutron star structures are calculated using several parameter sets, and the results for the nuclear matter properties at saturation density align with empirical values. It is found that the neutron star structures are sensitive to the couplings between the iso-vector $a_{0}$ meson and nucleons and the four-vector meson couplings: small values of both are favorable. Meanwhile, nuclear matter properties at saturation density favor larger values of the latter and are not sensitive to the former. This signifies the statistical significance of neutron star observations when obtaining realistic chiral effective field theories or models at various densities. The parameter set favored by neutron star observations also aligns the behavior of the sound velocity with the conformal limit at high densities relevant to cores of massive stars. It is hoped that the results of this work can guide future studies on the relationship between the microscopic symmetry of strong interactions and macroscopic phenomena.
nucl-thastro-ph.HEPRD(2025)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Exact solutions of the nuclear shell-model secular problem: Discrete Non-Orthogonal Shell Model within a Variation After Projection approach

Bayesian approach for many-body uncertainties in nuclear structure: Many-body perturbation theory for finite nuclei

Pseudo-gauge invariant non-equilibrium density operator

Light and heavy Λ hyperclusters in nuclear matter with relativistic-mean-field models

Proton radioactivity in deformed nuclei with microscopic optical potential: A novel angular-dependent emission mechanism in the nanosecond-lived 149Lu

Composition of scalar mesons and their effects on nuclear matter properties in an extended linear sigma model

Affiliations

Light and heavy $Λ$ hyperclusters in nuclear matter with relativistic-mean-field models

Proton radioactivity in deformed nuclei with microscopic optical potential: A novel angular-dependent emission mechanism in the nanosecond-lived $^{149}$ Lu