Nuclear matrix elements of ββ decay from β-decay data

The evaluation of the nuclear matrix elements (NME) of the two-neutrino double beta (2nubetabeta) decay and neutrinoless double beta (0nubetabeta) decay using the proton-neutron quasiparticle random-phase approximation (pnQRPA) is addressed. In particular, the extraction of a proper value of the proton-neutron particle-particle interaction parameter, g(pp), of this theory is analyzed in detail. Evidence is shown, that it can be misleading to use the experimental half-life of the 2nubetabeta decay to extract a value for g(pp). Rather, arguments are given in favour of using the available data on single beta decay for this purpose. (C) 2004 Elsevier B.V. All rights reserved.