Temperature evolution of the nuclear shell structure and the dynamical nucleon effective mass

TL;DR

This paper investigates how the nuclear shell structure and the nucleon effective mass evolve with temperature in medium-mass nuclei, using finite-temperature Green functions and particle-vibration coupling to include correlations beyond mean field.

Contribution

It introduces a finite-temperature Dyson equation approach with dynamical particle-vibration coupling to study temperature effects on nuclear structure and effective mass.

Findings

Fragmentation of single-particle states increases with temperature

Dynamical nucleon effective mass varies significantly with temperature

Results relevant for understanding core-collapse supernovae

Abstract

We study the fermionic Matsubara Green functions in medium-mass nuclei at finite temperature. The single-fermion Dyson equation with the dynamical kernel of the particle-vibration-coupling (PVC) origin is formulated and solved in the basis of Dirac spinors, which minimize the grand canonical potential with the meson-nucleon covariant energy density functional. The PVC correlations beyond mean field are taken into account in the leading approximation for the energy-dependent self-energy, and the full solution of the finite-temperature Dyson equation is obtained for the fermionic propagators. Within this approach, we investigate the fragmentation of the single-particle states and its evolution with temperature for the nuclear systems $^{56,68}$Ni and $^{56}$Fe relevant for the core-collapse supernova. The energy-dependent, or dynamical, nucleon effective mass is extracted from the PVC self-energy at various temperatures.