Muon-Tau Symmetry and Leptogenesis in the Minimal Seesaw Model

TL;DR

This paper explores how muon-tau symmetry in the minimal seesaw model constrains neutrino masses and CP violation phases, and proposes using leptogenesis to determine additional parameters, including the effective neutrino mass for neutrinoless double beta decay.

Contribution

It demonstrates the parameter constraints of the minimal seesaw model under muon-tau symmetry and introduces leptogenesis as a method to determine additional CP phases.

Findings

Model supports at most 3 CP violation phases and 5 real masses at high energies.

Low-energy parameters are reduced to 4 masses and one Majorana phase.

Approximate reconstruction of the neutrino mass matrix and prediction of neutrinoless double beta decay parameter.

Abstract

The measured values for the mixture angles in neutrino oscillations suggest the existence of a symmetry of interchange of flavor between muon and tau neutrinos. Using this symmetry we analyzed the minimal seesaw model for neutrino masses, where the Majorana mass was diagonalized, and it is demonstrated that the model supports at most 3 CP violation phases and 5 real masses at high energies. Nevertheless, at low energies, only 4 parameters of mass and one relative Majorana CP phase remain. Therefore using the experimental values of the masses square differences, the mixture angles and the hierarchy, we can determine some parameters of the model but not all. Also we propose the use of the parameter of baryonic asymmetry of the universe due to leptogenesis to determine one more phase of the model. Finally we used a normal hierarchy for the masses of the right handed neutrinos to make an approximation, that allowed us to completely reconstruct the mass matrix for left handed neutrinos. In special the value of mee is determined which can be compared with the results of the neutrinoless double decay beta.