Mu-tau reflection symmetry with a high scale texture-zero

TL;DR

This paper combines mu-tau reflection symmetry with a discrete symmetry to predict neutrino masses and mixing, significantly reducing free parameters and constraining the absolute neutrino mass scale.

Contribution

It introduces a novel model that enforces a texture-zero in the heavy neutrino mass matrix, linking symmetry constraints to neutrino mass predictions and leptogenesis.

Findings

Neutrino mass scale restricted to a few discrete regions.

Heavy neutrino sector depends on only two parameters.

Successful leptogenesis further constrains model parameters.

Abstract

The $\mu\tau$-reflection symmetric neutrino mass matrix can accommodate all known neutrino mixing angles, with maximal atmospheric angle fixed, and predicts all the unknown CP phases of the lepton sector but is unable to predict the absolute neutrino mass scale. Here we present a highly predictive scenario where $\mu\tau$-reflection is combined with a discrete abelian symmetry to enforce a texture-zero in the mass matrix of the heavy right-handed neutrinos that generate the light neutrino masses. Such a restriction reduces the free parameters of the low energy theory to zero and the absolute neutrino mass scale is restricted to few discrete regions, three in the few meV range and one extending up to around 30 meV. The heavy neutrino sector is dependent only on two free parameters which are further restricted to small regions from the requirement of successful leptogenesis. Mass degenerate heavy neutrinos are possible in one case but there is no resonant enhancement of the CP asymmetry.