Leptonic mixing, family symmetries, and neutrino phenomenology

TL;DR

This paper analyzes tribimaximal and related mass-independent leptonic mixing schemes, exploring their group-theoretic origins, phenomenological predictions, and how to generalize models to other mixing patterns while maintaining their symmetry-phenomenology connection.

Contribution

It provides a classification of models based on family symmetries for tribimaximal mixing and introduces a method to generalize models to other mass-independent mixing schemes.

Findings

Group structure often directly relates to mixing phenomenology.

Seesaw mechanisms influence model viability and leptogenesis.

Explicit construction of models for various mixing patterns.

Abstract

Tribimaximal leptonic mixing is a mass-independent mixing scheme consistent with the present solar and atmospheric neutrino data. By conveniently decomposing the effective neutrino mass matrix associated to it, we derive generic predictions in terms of the parameters governing the neutrino masses. We extend this phenomenological analysis to other mass-independent mixing schemes which are related to the tribimaximal form by a unitary transformation. We classify models that produce tribimaximal leptonic mixing through the group structure of their family symmetries in order to point out that there is often a direct connection between the group structure and the phenomenological analysis. The type of seesaw mechanism responsible for neutrino masses plays a role here, as it restricts the choices of family representations and affects the viability of leptogenesis. We also present a recipe to generalize a given tribimaximal model to an associated model with a different mass-independent mixing scheme, which preserves the connection between the group structure and phenomenology as in the original model. This procedure is explicitly illustrated by constructing toy models with the transpose tribimaximal, bimaximal, golden ratio, and hexagonal leptonic mixing patterns.