Beyond-mean-field calculations of allowed and first-forbidden β− decays of r-process waiting-point nuclei

Caroline Robin,Elena Litvinova,Gabriel Martínez-Pinedo

doi:10.1051/epjconf/202226003002

Abstract

β-decay rates of neutron-rich nuclei, in particular those located at neutron shell closures, play a central role in simulations of the heavy-element nucleosynthesis and resulting abundance distributions. We present β-decay half-lives of even-even N = 82 and N = 126 r-process waiting-point nuclei calculated in the approach based on relativistic quasiparticle random phase approximation with quasiparticle-vibration coupling. The calculations include both allowed and first-forbidden transitions. In the N = 82 chain, the quasiparticlevibration coupling has an important impact close to stability, as it increases the contribution of Gamow-Teller modes and improves the agreement with the available data. In the N = 126 chain, we find the decay to proceed dominantly via first-forbidden transitions, even when the coupling to vibrations is included.

Highlights

Modeling the r-process nucleosynthesis requires a huge amount of nuclear physics input, and in particular, the knowledge of β-decay rates for thousands of neutron-rich nuclei
We present β-decay half-lives of even-even N = 82 and N = 126 r-process waiting-point nuclei calculated in the approach based on relativistic quasiparticle random phase approximation with quasiparticle-vibration coupling
Overall the predictions of these three Quasiparticle Random Phase Approximation (QRPA) frameworks disagree to some degree, in particular on the contribution of the FF transitions in different mass regions, and on the order of magnitude of the total half-lives above N > 126 which are predicted to be substantially lower by Ref. [2] than by the other two approaches

Summary

Introduction

Modeling the r-process nucleosynthesis requires a huge amount of nuclear physics input, and in particular, the knowledge of β-decay rates for thousands of neutron-rich nuclei. We present β-decay half-lives of even-even N = 82 and N = 126 r-process waiting-point nuclei calculated in the approach based on relativistic quasiparticle random phase approximation with quasiparticle-vibration coupling. In the N = 126 chain, we find the decay to proceed dominantly via first-forbidden transitions, even when the coupling to vibrations is included.

Results

Conclusion