Stellar weak decay rates in neutron-deficient medium-mass nuclei

TL;DR

This paper investigates weak decay rates of neutron-deficient medium-mass nuclei under stellar conditions relevant to the rp-process, using a detailed nuclear structure model to analyze decay mechanisms and sensitivities.

Contribution

It introduces a comprehensive study combining deformed Skyrme Hartree-Fock + BCS + QRPA calculations to evaluate stellar decay rates, including excited state contributions and electron capture effects.

Findings

Decay rates are sensitive to temperature and density variations.

Thermally populated excited states significantly influence decay rates.

Electron capture competes with beta decay under stellar conditions.

Abstract

Weak decay rates under stellar density and temperature conditions holding at the rapid proton capture process are studied in neutron-deficient medium-mass waiting point nuclei extending from Ni up to Sn. Neighboring isotopes to these waiting point nuclei are also included in the analysis. The nuclear structure part of the problem is described within a deformed Skyrme Hartree-Fock + BCS + QRPA approach, which reproduces not only the beta-decay half-lives but also the available Gamow-Teller strength distributions, measured under terrestrial conditions. The various sensitivities of the decay rates to both density and temperature are discussed. In particular, we study the impact of contributions coming from thermally populated excited states in the parent nucleus, as well as the competition between beta decays and continuum electron captures.