Large-Scale Calculations of $\beta$-Decay Rates and Implications for $r$-Process Nucleosynthesis

TL;DR

This paper presents advanced global calculations of nuclear $eta$-decay rates using relativistic density functional theory, revealing slower decay rates near the neutron drip line and implications for heavy element synthesis in the $r$-process.

Contribution

It introduces a new set of $eta$-decay rates based on relativistic models, improving predictions near the neutron drip line and impacting $r$-process nucleosynthesis models.

Findings

Slower $eta$ decays past the $N=126$ shell closure.

Reduced contribution of neutron-induced fission.

Consistent results across different functionals.

Abstract

Nuclear $\beta$ decay is a key element of the astrophysical rapid neutron capture process ($r$-process). In this paper, we present state-of-the-art global $\beta$-decay calculations based on the quantified relativistic nuclear energy density functional theory and the deformed proton-neutron quasiparticle random-phase approximation. Our analysis considers contributions from allowed and first-forbidden transitions. We used two point-coupling functionals with carefully calibrated time-odd terms and isoscalar pairing strength. The new calculations display consistent results for both employed functionals, especially near the neutron drip line, suggesting slower $\beta$ decays past the $N=126$ neutron shell closure than in commonly used $\beta$-decay models. The new rates, along with the existing rates based on the latest non-relativistic calculations, are found to slow down the synthesis of heavy elements in the $r$-process and significantly reduce the contribution of neutron-induced fission.