A review of mu-tau flavor symmetry in neutrino physics

TL;DR

This review discusses mu-tau flavor symmetry in neutrino physics, exploring its theoretical features, implications for models, and the importance of symmetry breaking for understanding neutrino mixing and CP violation.

Contribution

It provides a comprehensive overview of mu-tau symmetry, including permutation and reflection types, and emphasizes the role of symmetry breaking in neutrino phenomenology.

Findings

Mu-tau symmetry explains observed lepton mixing patterns.

Soft symmetry breaking is essential for CP violation insights.

Implications for neutrino mass models are discussed.

Abstract

Behind the observed pattern of lepton flavor mixing is a partial or approximate mu-tau flavor symmetry --- a milestone on our road to the true origin of neutrino masses and flavor structures. In this review article we first describe the features of mu-tau permutation and reflection symmetries, and then explore their various consequences on model building and neutrino phenomenology. We pay particular attention to soft mu-tau symmetry breaking, which is crucial for our deeper understanding of the fine effects of flavor mixing and CP violation.