# Time-reversed particle-vibration loops and nuclear Gamow-Teller response

## TL;DR

This paper extends nuclear response theory to include particle-vibration coupling effects in the ground state, significantly improving the description of Gamow-Teller transitions and matching experimental data.

## Contribution

It introduces for the first time particle-vibration coupling effects in the ground state within a relativistic framework for charge-exchange modes.

## Key findings

- Particle-vibration coupling explains the (n,p) strength in Gamow-Teller transitions.
- Results show excellent agreement with experimental data up to high excitation energies.
- Parent-daughter binding-energy differences are significantly improved.

## Abstract

The nuclear response theory for charge-exchange modes in the relativistic particle-vibration coupling approach is extended to include for the first time particle-vibration coupling effects in the ground state of the parent nucleus. In a framework based on the effective meson-nucleon Lagrangian, we investigate the role of such complex ground-state correlations in the description of Gamow-Teller transitions in $^{90}$Zr in both (p,n) and (n,p) channels. The particle-vibration coupling effects are calculated without introducing new parameters. We find that this new correlation mechanism is fully responsible for the appearance of the strength in the (n,p) branch. Comparison of our results to the available experimental data shows a very good agreement up to excitation energies beyond the giant resonance region when taking into account a phenomenological admixture of the isovector spin monopole transitions. The parent-daughter binding-energy differences are also greatly improved by the inclusion of the new correlations.