Gamow-Teller decays: Probing nuclear structure and weak interactions

We describe the Gamow-Teller decays for nuclear systems outside the 40 Ca and 56 Ni closed cores in the framework of the realistic shell model, starting from a nuclear Hamiltonian and electroweak currents as consistently obtained by means of chiral perturbation theory. The effective shell-model Hamiltonians and decay operators are derived using many-body perturbation theory, allowing the role of both electroweak currents and many-body correlations to be taken into account as the origin of the problem of the quenching of the axial coupling constant g A .