Neutrino masses, mixing, Majorana CP-violating phases and (beta beta)0 nu decay

Predictions of the effective Majorana mass [m] in (betabeta)(0nu) decay for 3-nu mixing and massive Majorana neutrinos are reviewed in the present study. The physics potential of the experiments, searching for (betabeta)(0nu) decay and having sensitivity to [m] greater than or similar to 0.01 eV for providing information on the type of the neutrino mass spectrum, the absolute scale of neutrino masses and on the Majorana CP-violation phases in the PMNS neutrino mixing matrix, is also discussed.