Atmospheric neutrino oscillation and a phenomenological lepton mass matrix

Abstract

We propose simple phenomenological lepton mass matrices which describe the three neutrinos almost degenerate in mass, leading to a very large mixing angle between ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\ensuremath{\nu}}_{\ensuremath{\tau}},$ as consistent with a recent report on atmospheric neutrino oscillations from the SuperKamiokande Collaboration. Our matrix model also gives ${\ensuremath{\nu}}_{e}\ensuremath{-}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ mixing in agreement with the value required for neutrino oscillation to explain the solar neutrino problem.