Abstract

We revisit the mechanism of neutrinoless double beta (0 nu beta beta) decay mediated by the exchange with the heavy Majorana neutrino N of arbitrary mass m(N), slightly mixed similar to U-eN with the electron neutrino nu(e). By assuming the dominance of this mechanism, we update the well-known 0 nu beta beta-decay exclusion plot in the m(N) - U-eN plane taking into account recent progress in the calculation of nuclear matrix elements within quasiparticle random phase approximation and improved experimental bounds on the 0 nu beta beta-decay half-life of Ge-76 and Xe-136. We also consider the known formula approximating the m(N) dependence of the 0 nu beta beta-decay nuclear matrix element in a simple explicit form. We analyze its accuracy and specify the corresponding parameters, allowing one to easily calculate the 0 nu beta beta-decay half-life for arbitrary m(N) for all the experimentally interesting isotopes without resorting to real nuclear structure calculations.