Neutrino oscillation constraints on neutrinoless double-beta decay

We have studied the constraints imposed by the results of neutrino oscillation experiments on the effective Majorana mass \[m]\ that characterizes the contribution of Majorana neutrino masses to the matrix element of neutrinoless double-beta decay. We have shown that in a general scheme with three Majorana neutrinos and a hierarchy of neutrino masses (which corresponds to the standard seesaw mechanism) the results of neutrino oscillation experiments imply rather strong constraints on the parameter \[m]\ From the results of the first reactor long-baseline experiment CHOOZ and the Bugey experiment it follows that \[m]\less than or similar to 3X10(-2) eV if Delta m(2) less than or similar to 2 eV(2) (Delta m(2) is the largest mass-squared difference). Hence, we conclude that the observation of neutrinoless double-beta decay with a probability that corresponds to \[m]\greater than or similar to 10(-1) eV would be a signal for a nonhierarchical neutrino mass spectrum and/or nonstandard mechanisms of lepton number violation.