Statistical analysis of β decays and the effective value of gA in the proton-neutron quasiparticle random-phase approximation framework

Abstract

We perform a Markov chain Monte Carlo (MCMC) statistical analysis of a number of measured groundstate-to-ground-state single β+/electron-capture and β− decays in the nuclear mass range of A = 62–142. The corresponding experimental comparative half-lives (log f t values) are compared with the theoretical ones obtained by the use of the proton-neutron quasiparticle random-phase approximation (pnQRPA) with G-matrixbased effective interactions. The MCMC analysis is performed separately for 47 isobaric triplets and 28 more extended isobaric chains of nuclei to extract values and uncertainties for the effective axial-vector coupling constant gA in nuclear-structure calculations performed in the pnQRPA framework. As far as available, measured half-lives for two-neutrino ββ− decays occurring in the studied isobaric chains are analyzed as well.