A Minimal See-Saw Model for Hierarchical Neutrino Masses with Large Mixing

TL;DR

This paper proposes a minimal see-saw model with two heavy right-handed neutrinos that naturally explains hierarchical neutrino masses and large mixing angles observed in atmospheric and solar neutrino oscillations.

Contribution

It introduces a simple U(1) extended model with flavor-dependent charges, providing a natural explanation for neutrino mass hierarchy and mixing patterns.

Findings

Successfully accounts for large atmospheric neutrino mixing.

Explains small solar neutrino mixing within the model.

Maintains hierarchical neutrino mass structure.

Abstract

The atmospheric and solar neutrino oscillation data suggest hierarchical neutrino masses with at least one large mixing. The simplest see-saw models for reconciling the two features are U(1) extensions of the SM with flavour dependent gauge charges. I discuss a minimal model of this type containing two heavy right-handed neutrinos, which have normal Dirac couplings to $\nu_\mu$ and $\nu_\tau$ but suppressed ones to $\nu_e$. It can naturally account for the large (small) mixing solutions to the atmospheric (solar) neutrino oscillation data.