NEUTRINO MASS-SPECTRUM FROM THE RESULTS OF NEUTRINO OSCILLATION EXPERIMENTS

All the possible schemes of neutrino mixing with four massive neutrino s inspired by the existing experimental indications in favor of neutri no mixing are considered in a model independent way. Assuming that in short-baseline experiments only one mass-squared difference is relevan t, it is shown that the scheme with a neutrino mass hierarchy is not c ompatible with the experimental results. Only two schemes with two pai rs of neutrinos with close masses separated by a mass difference of th e order of 1 eV are in agreement with the results of all experiments. One of these schemes leads to possibly observable effects in H-3 and ( beta beta)(0V) experiments.