Shell-model study of weak β-decays relevant to astrophysical processes

Shell-model studies on the weak β-decay in nuclei relevant to astrophysical processes are carried out. The β-decay rates, as well as electron-capture rates in the sd-pf shell induced by Gamow–Teller (GT) transition, are evaluated in astrophysical environments. The weak rates for the Urca pair of nuclei with A = 31 in the island of inversion, which are important for the nuclear Urca processes in neutron star crusts, are investigated by shell-model calculations in the sd–pf shell. The GT strength is evaluated in the sd–pf shell for selected β-decays in the sd-shell nuclei, and the effects of the expansion of the configuration space on the quenching of the axial–vector coupling are examined. β-decay rates induced by first-forbidden (FF) transitions are studied by the Behrens–Bühring (BB) method for the isotones with N = 126 and compared with the Walecka method. The important role of the electron distortions in the β-decays of 206Hg and 207Tl is pointed out.