On the neutrino mass spectrum and neutrino mixing from oscillation data

Abstract

Two schemes of mixing of four massive neutrinos with two couples of close neutrino masses separated by a gap of the order of eV can accommodate solar, atmospheric and LSND neutrinos oscillation data. It is shown that long-baseline ν e → ν e and ν μ → ν e transitions are strongly suppressed in these schemes. The scheme of mixing of three neutrino masses with a mass hierarchy that can describe solar and atmospheric neutrino data is also discussed. It is shown that in this scheme the effective Majorana mass |〈 m〉|b that characterizes the matrix element of neutrinoless double-β decay is less than ∼10 −2 eV.