Self-consistent renormalized quasiparticle random phase approximation and its application to 2νββ and 0νββ decays

Abstract

We have used a self-consistent version of the BCS + RQRPA method for a systematic study of the two-neutrino double-beta decay of nuclei with 100<A≤150. We also applied this newly derived formalism, to the 0νββ decay of 76Ge, where the induced nucleon currents have been accounted for. The results have been compared to the previously used approaches, namely the QRPA and the RQRPA approximations. We have shown that inclusion of the quasiparticle correlations at the BCS level reduces ground state correlations in the particle-particle channel of the proton-neutron interaction. This gives the systematic and considerable reduction of the double-beta-decay matrix elements, resulting in less stringent limits for the effective neutrino mass.