Theory Review of Neutrino Models and CP Violation

TL;DR

This paper reviews various neutrino mixing models, focusing on how discrete symmetries and CP violation influence their predictions, especially after the reactor angle measurement challenged traditional models.

Contribution

It provides a comprehensive overview of neutrino models incorporating non-Abelian discrete symmetries and CP symmetry, highlighting their theoretical origins and phenomenological implications.

Findings

Charged lepton corrections modify tribimaximal mixing.

Remnants of non-Abelian discrete symmetries predict specific mixing patterns.

Modular symmetry may underpin the origin of these discrete groups.

Abstract

Although the measurement of the reactor angle has killed tribimaximal lepton mixing, its descendants survive with charged lepton corrections, or in less constrained forms such as trimaximal mixing and/or mu-tau symmetry, each with characteristic predictions. Such patterns may be enforced by a remnant of some non-Abelian discrete family symmetry, possibly together with a generalised CP symmetry, which could originate from continuous gauge symmetry and/or superstring theory in compactified extra dimensions, as a finite subgroup of the modular symmetry.