Tri-bimaximal Mixing from Cascades

TL;DR

This paper investigates fermion mass matrices of cascade form that align with tri-bimaximal lepton mixing, revealing parameter-independent relations among mixing angles and mass eigenvalues, and explores phenomenological implications and theoretical origins.

Contribution

It introduces cascade mass matrices compatible with tri-bimaximal mixing, deriving parameter-independent relations and discussing their phenomenological and theoretical foundations.

Findings

Atmospheric neutrino mixing angle is close to maximal.

Relations among mixing angles and mass eigenvalues are parameter-independent.

Phenomenological implications include flavor-violating decays and leptogenesis.

Abstract

We study fermion mass matrices of the cascade form which are compatible with the tri-bimaximal lepton mixing and generation mass hierarchy. The flat-cascade lepton matrices imply a parameter-independent relation among the mixing angles and mass eigenvalues. The relation has several indications that the atmospheric neutrino mixing angle is close to maximal and the other two angles have a correlation independently of neutrino mass eigenvalues. We also discuss phenomenological aspects of the cascade matrices; flavor-violating rare decays of charged leptons, thermal leptogenesis, and leptonic CP violation. Possible dynamical origins of the cascades are illustrated based on flavor symmetry and in higher-dimensional theory.