On the breaking of mu-tau flavor symmetry

TL;DR

This paper explores how breaking mu-tau flavor symmetry can explain the observed large mixing angle theta_13 in neutrino oscillations, analyzing various symmetry-breaking patterns and their phenomenological viability.

Contribution

It systematically investigates different symmetry-breaking patterns and discusses the effects of physics like renormalization group running on mu-tau symmetry.

Findings

Certain symmetry-breaking patterns are phenomenologically viable.

Renormalization group effects can induce mu-tau symmetry breaking.

The study clarifies the role of symmetry breaking in neutrino mixing angles.

Abstract

In light of the observation of a relatively large $\theta^{}_{13}$, one has to consider breaking the $\mu$-$\tau$ symmetry properly which would otherwise result in a vanishing $\theta^{}_{13}$ (as well as $\theta^{}_{23} = \pi/4$). Therefore, we investigate various symmetry-breaking patterns and accordingly identify those that are phenomenologically viable. Furthermore, the symmetry-breaking effects arising from some specific physics (e.g., the renormalization group equation running effect) are discussed as well.