Shell-model study for allowed and forbidden β− decay properties in the mass region “south” of Pb208

The large-scale shell-model calculations have been performed for the neutron-rich nuclei in the south region of ²⁰⁸Pb in the nuclear chart. The β-decay properties, such as the $logft$, average shape factor values, half-lives, and partial decay rates are calculated for these neutron-rich nuclei using recent effective interaction for the ²⁰⁸Pb region. These calculations have been performed without truncation in a particular model space for nuclei N≤126; additionally, particle-hole excitations are included in the case of core-breaking nuclei (Z≤82,N>126). An extensive comparison with the experimental data has been made, and spin parities of several states have been proposed.