Large or Small Angle MSW from Single Right-Handed Neutrino Dominance

TL;DR

This paper explores how a single right-handed neutrino can naturally explain neutrino mass hierarchies and large mixing angles, with models accommodating both small and large angle MSW solutions.

Contribution

It introduces a mechanism where one right-handed neutrino dominates, and demonstrates its application in U(1) family symmetry models for both small and large angle MSW solutions.

Findings

Single right-handed neutrino dominance explains neutrino mixing.

Models can naturally produce quark and lepton mass hierarchies.

Explicit examples for small and large angle MSW solutions are provided.

Abstract

In this talk we discuss a natural explanation of both neutrino mass hierarchies {\it and} large neutrino mixing angles, as required by the atmospheric neutrino data, in terms of a single right-handed neutrino giving the dominant contribution to the 23 block of the light effective neutrino matrix, and illustrate this mechanism in the framework of models with U(1) family symmetries. Sub-dominant contributions from other right-handed neutrinos are required to give small mass splittings appropriate to the MSW solution to the solar neutrino problem. We present three explicit examples for achieving the small angle MSW solution in the framework of U(1) family symmetry models containing three right-handed neutrinos, which can naturally describe all quark and lepton masses and mixing angles. In this talk we also extend the analysis to the large angle MSW solution.