Scaling ansatz, four zero Yukawa textures, and largeθ13

Abstract

We investigate the ``scaling Ansatz'' in the neutrino sector within the framework of a type-I seesaw mechanism with diagonal charged lepton and right-handed Majorana neutrino mass matrices (${M}_{R}$). We also assume the four zero texture of Dirac neutrino mass matrices (${m}_{D}$) which severely constrain the phenomenological outcomes of such schemes. The scaling Ansatz and the present neutrino data allow only six such matrices out of 126 four zero Yukawa matrices. In this scheme, in order to generate large ${\ensuremath{\theta}}_{13}$, we break the scaling Ansatz in ${m}_{D}$ through a perturbation parameter and we also show that our breaking scheme is radiatively stable. We further investigate $CP$ violation and baryogenesis via leptogenesis in those surviving textures.