Toward exploring unknowns in the lepton flavor mixing

Abstract

In this talk I focus in on some of the relatively unexplored aspects of neutrino masses and lepton flavor mixing. They are (1) possible deviation of θ 23 from the maximal, and (2) serious consequences of our ignorance of the sign of Δ m 2 13 on the interpretation of future CP violation measurement. I emphasize that the accuracy of s 2 23 determination that already achieved by the Super-Kamiokande atmospheric neutrino observation will not be improved significantly by the next-generation LBL experiments for nearly maximal θ 23 . I also stress that, unless we know the sign of Δ m 2 13 , detection of CP violation in the JPARC-SK experiment would suffer from the problem of confusion to CP conservation. Clearly, better strategies which so far escaped our attention are called for to determine these quantities.