Atmospheric neutrino oscillation and a phenomenological lepton mass matrix

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