Democratic Mass Matrices from Broken $O(3)_L\times O(3)_R$ Flavor Symmetry

TL;DR

This paper proposes a flavor symmetry breaking mechanism in a supersymmetric standard model that naturally produces democratic mass matrices, explaining large neutrino mixing and quark mass hierarchies.

Contribution

It introduces a novel $O(3)_L\times O(3)_R$ flavor symmetry breaking approach that yields realistic lepton and quark mass matrices, including nearly degenerate neutrino masses.

Findings

Large $ u_ au- u_ au$ mixing is naturally obtained.

Neutrino masses are nearly degenerate around 0.1 eV.

Model is consistent with observed quark mass hierarchies and CKM matrix.

Abstract

We impose $O(3)_L\times O(3)_R$ flavor symmetry in the supersymmetric standard model. Three lepton doublets $\ell_i$ transform as an $O(3)_L$ triplet and three charged leptons $\bar e_i$ as an $O(3)_R$ triplet, while Higgs doublets $H$ and $\bar H$ are $O(3)_L\times O(3)_R$ singlets. We discuss a flavor $O(3)_L\times O(3)_R$ breaking mechanism that leads to "successful" phenomenological mass matrices, so-called "democratic" ones, in which the large $\n_\mu-\n_\tau$ mixing is naturally obtained. Three neutrinos have nearly degenerate masses of order $0.1\eV$ which may be accesible to future double $\b$-decay experiments. We extend our approach to the quark sector and show that it is well consistent with the observed quark mass hierarchies and the CKM matrix elements. However, the large mass of the top quark requires a relatively large coupling. constant.