Neutrinoless double beta decays of 106Cd revisited

Neutrinoless double beta (0ν2β) decays of 106Cd are studied for the transitions to the ground state, 0gs+, and 0+ excited states in 106Pd by using realistic many-body wave functions calculated in the framework of the quasiparticle random-phase approximation and its extensions. Effective, G-matrix-based nuclear forces are used in large single-particle model spaces. Both the β+β+ and β+EC channels of the 0ν2β decay are discussed and half-lives are computed. Particular attention is devoted to the study of the detectability of the resonant neutrinoless double electron capture (R0νECEC) process in 106Cd. The calculations of the present article constitute the thus far most complete and up-to-date investigation of the 0ν2β properties of 106Cd.