The Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling

TL;DR

This paper extends the Skyrme RPA model by including particle-vibration coupling to better understand the Gamow-Teller response in nuclei, especially its low-lying strength relevant for astrophysical processes.

Contribution

It introduces a consistent model that incorporates particle-vibration coupling into RPA calculations of the Gamow-Teller response, going beyond mean-field approximations.

Findings

Particle-vibration coupling redistributes low-lying GT$^+$ strength.

The model's predictions align with experimental fragmentation and lowering of strength.

The total low-lying strength quenching remains unexplained by the model.

Abstract

Although many random-phase approximation (RPA) calculations of the Gamow-Teller (GT) response exist, this is not the case for calculations going beyond the mean-field approximation. We apply a consistent model that includes the coupling of the GT resonance to low-lying vibrations, to nuclei of the $fp$ shell. Among other motivations, our goal is to see if the particle-vibration coupling can redistribute the low-lying GT$^+$ strength that is relevant for electron-capture processes in core-collapse supernova. We conclude that the lowering and fragmentation of that strength are consistent with the experimental findings and validate our model. However, the particle-vibration coupling cannot account for the quenching of the total value of the low-lying strength.