Influence of 2p-2h configurations on beta-decay rates

TL;DR

This paper investigates how phonon-phonon coupling and 2p-2h configurations influence beta-decay rates in neutron-rich nuclei using a microscopic Skyrme-based model, revealing significant reductions in half-lives and providing predictions for key isotopes.

Contribution

It introduces a microscopic model incorporating 2p-2h configurations and tensor correlations to accurately predict beta-decay rates in neutron-rich nuclei.

Findings

Gamow-Teller strength redistribution due to tensor correlations

Significant decrease in beta-decay half-lives

Predictions for 76Fe and 80Ni isotopes

Abstract

The effects of the phonon-phonon coupling on the beta-decay rates of neutron-rich nuclei are studied in a microscopic model based on Skyrme-type interactions. The approach uses a finite-rank separable approximation of the Skyrme-type particle-hole (p-h) residual interaction. Very large two-quasiparticle spaces can thus be treated. A redistribution of the Gamow-Teller (G-T) strength is found due to the tensor correlations and the 2p-2h fragmentation of G-T states. As a result, the beta-decay half-lives are decreased significantly. Using the Skyrme interaction SGII together with a volume-type pairing interaction we illustrate this reduction effect by comparing with available experimental data for the Ni isotopes and neutron-rich N=50 isotones. We give predictions for 76Fe and 80Ni in comparison with the case of the doubly-magic nucleus 78Ni which is an important waiting point in the r-process.