  We report on the calculation of Gamow-Teller and double-beta decay properties
for nuclei around 132Sn within the framework of the realistic shell model. The
effective shell-model Hamiltonian and Gamow-Teller transition operator are
derived by way of many-body perturbation theory, without resorting to empirical
effective quenching factor for the Gamow-Teller operator. The results are then
compared with the available experimental data, in order to establish the
reliability of our approach. This is a mandatory step, before we apply the same
methodology, in forthcoming studies, to the calculation of the neutrinoless
double-beta decay nuclear matrix element for nuclei that are currently
considered among the best candidates for the detection of this process.
