Nuclear Shell Structure in a Finite-Temperature Relativistic Framework

TL;DR

This paper investigates how neutron-rich nuclear shell structures evolve with temperature using a advanced relativistic framework that incorporates particle-vibration coupling, providing insights relevant to astrophysical conditions.

Contribution

It introduces a finite-temperature relativistic approach with particle-vibration coupling to study shell evolution in neutron-rich nuclei, extending beyond mean-field models.

Findings

Fragmentation patterns of single-particle states depend on temperature.

Toy models quantify sensitivity of fragmentation to phonon properties.

Insights into temperature effects on nuclear shell structure in astrophysical environments.

Abstract

The shell evolution of neutron-rich nuclei with temperature is studied in a beyond-mean-field framework rooted in the meson-nucleon Lagrangian. The temperature-dependent Dyson equation with the dynamical kernel taking into account the particle-vibration coupling (PVC) is solved for the fermionic propagators in the basis of the thermal relativistic mean-field Dirac spinors. The calculations are performed for $^{68-78}$Ni in a broad range of temperatures $0 \leq T \leq 4$ MeV. The special focus is put on the fragmentation pattern of the single-particle states, which is further investigated within toy models in strongly truncated model spaces. Such models allow for quantifying the sensitivity of the fragmentation to the phonon frequencies, the PVC strength and to the mean-field level density. The model studies provide insights into the temperature evolution of the PVC mechanism in real nuclear systems under the conditions which may occur in astrophysical environments.