Large scale evaluation of beta-decay rates of r-process nuclei with the inclusion of first-forbidden transitions

TL;DR

This study systematically evaluates beta-decay rates of r-process nuclei using covariant density functional theory, highlighting the significant role of first-forbidden transitions in nuclei far from stability.

Contribution

It provides the first comprehensive, self-consistent calculation of beta-decay half-lives including first-forbidden transitions for all relevant r-process nuclei.

Findings

First-forbidden transitions significantly affect decay rates in neutron-rich nuclei.

The model reproduces experimental half-lives well for various nuclear types.

Including first-forbidden transitions improves decay rate predictions.

Abstract

R-process nucleosynthesis models rely, by necessity, on nuclear structure models for input. Particularly important are beta-decay half-lives of neutron rich nuclei. At present only a single systematic calculation exists that provides values for all relevant nuclei making it difficult to test the sensitivity of nucleosynthesis models to this input. Additionally, even though there are indications that their contribution may be significant, the impact of first-forbidden transitions on decay rates has not been systematically studied within a consistent model. We use a fully self-consistent covariant density functional theory (CDFT) framework to provide a table of $\beta$-decay half-lives and $\beta$-delayed neutron emission probabilities, including first-forbidden transitions. We observe a significant contribution of the first-forbidden transitions to the total decay rate in nuclei far from the valley of stability. The experimental half-lives are in general well reproduced, both for even-even, odd-A and odd-odd nuclei, in particular for short-lived nuclei.