Probing the quenching of gA by single and double beta decays

Ground-state-to-ground-state two-neutrino double beta (2 nu beta beta) decays and single beta (EC and beta(-)decays are studied for the A = 100 (Mo-100-Tc-100-Ru-100) A = 116 (Cd-116-In-116-Sn-116) and A = 128 (128Te-128I-128 Xe) nuclear systems by using the proton-neutron quasiparticle random-phase approximation exploiting realistic effective interactions in very large single-particle bases. The aim of this exercise is to see if both the single-beta and double-beta decay observables related to the ground states of the initial, intermediate and final nuclei participant in the decays can be described simultaneously by changing the value of the axial-vector coupling constant gA. In spite of the very different responses to single and 2 nu beta beta decays of the considered nuclear systems, the obtained results point consistently to a quenched effective value of gA that is (slightly) different for the single and 2 nu beta beta decays. (C) 2013 Elsevier B.V. All rights reserved.