Trimaximal lepton mixing with a trivial Dirac phase

TL;DR

This paper introduces a neutrino mixing model using the seesaw mechanism with five right-handed neutrinos, achieving trimaximal and CP-conserving mixing, and allows leptogenesis even with exact tri-bimaximal mixing.

Contribution

It presents a novel model that combines the seesaw mechanism with five right-handed neutrinos to realize trimaximal and CP-conserving lepton mixing, including a natural limit to tri-bimaximal mixing.

Findings

Model achieves trimaximal and CP-conserving lepton mixing.

Tri-bimaximal mixing emerges as a natural limit.

Leptogenesis is possible even with exact tri-bimaximal mixing.

Abstract

We present a model which employs the seesaw mechanism with five right-handed neutrinos, leading to trimaximal and CP-conserving lepton mixing. Tri-bimaximal mixing is a natural limiting case of our model which occurs when one particular vacuum expectation value is real and preserves the mu-tau interchange symmetry of the Lagrangian. Our model allows for leptogenesis even in the case of exact tri-bimaximal mixing.