Atmospheric and Solar Neutrinos from Single Right-Handed Neutrino Dominance and U(1) Family Symmetry

TL;DR

This paper proposes a model where a single right-handed neutrino dominates the neutrino mass matrix, explaining neutrino hierarchies and mixing angles through U(1) family symmetry, aligning with atmospheric and solar neutrino data.

Contribution

It introduces a mechanism with a dominant right-handed neutrino contribution within U(1) symmetry models, providing a natural explanation for neutrino mass hierarchies and mixing angles.

Findings

Single right-handed neutrino dominates the 23 block of the neutrino mass matrix.

Sub-dominant contributions from other neutrinos produce small mass splittings.

Neutrino hierarchies and mixing angles can be expressed using the Wolfenstein parameter.

Abstract

We argue that in order to provide a natural explanation of both neutrino mass hierarchies and large neutrino mixing angles, as required by the atmospheric neutrino data, a single right-handed neutrino must give 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 small angle MSW solution to the solar neutrino problem. We give general conditions for achieving this in the framework of U(1) family symmetry models containing arbitrary numbers of right-handed neutrinos, and show how the resulting neutrino mass hierarchies and mixing angles may be expanded in terms of the Wolfenstein parameter.