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

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 + quasiparticle random-phase-approximation approach, which reproduces not only the β-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 and the competition between β decays and continuum electron captures.