Froggatt-Nielsen hierarchy and the neutrino mass matrix

Abstract

We study the neutrino mass matrix derived from the seesaw mechanism in which the neutrino Yukawa couplings and the heavy Majorana neutrino mass matrix are controlled by the Froggatt-Nielsen mechanism. In order to obtain the large neutrino mixings, two Froggatt-Nielsen fields are introduced with a complex vacuum expectation values. As a by-product, CP violation is systematically induced even if the order one couplings of FN fields are real. We show several predictions of this model, such as theta_{13}, the Dirac CP phase, two Majorana CP phases, the effective mass of the neutrinoless double beta decay and the leptogenesis. The prediction of the branching ratio of mu to e+gamma is also given in SUSY model.