Lepton Flavor Mixing and the Neutrino Masses : Attainments and Near Future Perspective

Abstract

A summary is given mainly from experimental aspects for development of physics of neutrino masses and lepton flavor mixing over the last 15 years. Starting from the 1998 discovery of neutrino oscillation and measurement of θ_<23> and Δm^2_<32> by the Super-Kamiokande atmospheric neutrino experiment, I describe measurement of θ_<12> and Δm^2_<21> by the KamLAND reactor and the solar neutrino experiments, and then determination of θ_<13> executed in the last one year or so. Thus, all the three mixing angles in the three-flavor mixing scheme of leptons have been determined. Implications of the large values of the lepton mixing angles compared to quark's as well as possible goal of the flavor physics is discussed. Finally, a near future perspective is given for determining the remaining unknowns, lepton CP violating phase and the neutrino mass pattern.