Constraints from neutrino oscillation experiments on the effective Majorana mass in neutrinoless double β-decay

We determine the possible values of the effective Majorana neutrino mass |〈m〉|=|∑jUej2mj| in the different phenomenologically viable three and four-neutrino scenarios. The quantities Uαj (α=e,μ,τ,…) denote the elements of the neutrino mixing matrix and the Majorana neutrino masses mj (j=1,2,3,…) are ordered as m1