Calculation of double beta decay rates and the neutrino mass

Abstract

Predictions for 2 v and 0 v double beta decay rates are given for all nuclei with A ⩾ 70, for which double beta decay is energetically allowed. These predictions are based on detailed nuclear structure studies of the beta strength distribution and replace earlier estimates basing mostly on phase space considerations. New and more stringent limits on the Majorana neutrino mass are deduced from existing double beta decay experiments. Since the collective effects arising from spin-isospin as well as quadrupole-quadrupole forces are found to lead to a strong reduction of the nuclear matrix elements for two-neutrino double beta decay, but to have only minor influence on the matrix elements M 0 v for the neutrinoless decay mode, the smaller limits for m v result mainly from the fact that the widely used scaling procedure underestimates the 0 v matrix elements. It is further discussed to what extent interference between different neutrinos affects the obtained mass limits.