The role of Majorana CP phases in the bi-maximal mixing scheme -hierarchical Dirac mass case-

Abstract

We discuss the energy scale profile of the bi-maximal mixing which is given at the GUT energy scale in the minimal SUSY model, associated with an assumption that Y_nu^dagger Y_nu is diagonal, where Y_nu is the neutrino-Yukawa coupling matrix. In this model, the Dirac mass matrix which appears in the seesaw neutrino mass matrix is determined by three neutrino masses, two relative Majorana phases and three heavy Majorana masses. All CP phases are related by two Majorana phases. We show that the requirement that the solar mixing angle moves from the maximal mixing at GUT to the observed one as the energy scale decreases by the renormalization effect. We discuss the leptogenesis, and the lepton flavor violation process by assuming the universal soft breaking terms.