Neutrino Mass Matrix, Mixing and Oscillation

We investigate the phenomenological consequences of lepton mass matrices originated from the family permutation symmetry and its suitable breakings. Adopting the recently proposed new mass matrix for the charged lepton mass matrix and the Majorana neutrino mass matrix considered before, we find that the resulting lepton flavor mixing matrix is consistent with the current data on various type of neutrino oscillation experiments except the Chlorine data and LSND measurement and that three neutrinos are almost degenerate in mass. Numerically the three neutrinos can account for about 50% of the hot dark matter(HDM) when the neutrino mass matrix is constrained by the small angle MSW solution for the solar neutrino problem, atmospheric neutrino data of the Super-Kamiokande group, and the limitation on the electron-type neutrino mass due to non-observation of neutrino-less double beta decays.