Fermion masses and proton decay in string-inspired SU(4)*SU(2)^2*U(1)_X

TL;DR

This paper proposes a supersymmetric model based on an SU(4)*SU(2)^2*U(1)_X gauge symmetry that explains fermion masses, neutrino mixing, and suppresses proton decay via anomaly cancellation mechanisms.

Contribution

It introduces a novel supersymmetric framework with specific gauge symmetry and matter content, providing a new approach to fermion mass hierarchies and proton stability.

Findings

Hierarchical neutrino masses with bi-large mixing achieved.

Proton decay operators are suppressed by anomaly cancellation.

Distinct Yukawa matrices due to group contractions.

Abstract

We present a supersymmetric model of fermion masses with SU(4)*SU(2)^2*U(1)_X gauge group with matter in fundamental and antisymmetric tensor representations only. The up, down, charged lepton and neutrino Yukawa matrices are distinguished by different Clebsch-Gordan coefficients due to contracting over SU(4) and SU(2)_R indices. We obtain a hierarchical light neutrino mass spectrum with bi-large mixing. The condition that anomalies be cancelled by a Green-Schwarz mechanism leads to fractional U(1)_X charges which exclude $B$ violation through dimension-4 and -5 operators.