An Improved Supersymmetric SU(5)

TL;DR

This paper presents an improved supersymmetric SU(5) model that explains fermion mass hierarchies, neutrino oscillations, and predicts a proton lifetime, by extending the minimal model with additional symmetries and matter multiplets.

Contribution

It introduces a novel supersymmetric SU(5) model with a flavor symmetry and extra matter multiplets, resolving previous mass relation issues and neutrino puzzles.

Findings

Predicts strong coupling constant α_s(M_Z) ≈ 0.115

Proton lifetime about five times larger than minimal model

Explains neutrino oscillation data with specific mixing angles

Abstract

By supplementing minimal supersymmetric SU(5) (MSSU(5)) with a flavor ${\cal U}(1)$ symmetry and two pairs of $\bar{15}+15$ `matter' supermultiplets, we present an improved model which explains the charged fermion mass hierarchies and the magnitudes of the CKM matrix elements, while avoiding the undesirable asymptotic mass relations $m_s=m_{\mu}, m_d/m_s = m_e/m_{\mu}$. The strong coupling $\alpha_s (M_Z)$ is predicted to be approximately 0.115, and the proton lifetime is estimated to be about five times larger than the MSSU(5) value. The atmospheric and solar neutrino puzzles are respectively resolved via maximal $\nu_{\mu}-\nu_{\tau}$ and small mixing angle $\nu_e-\nu_s$ MSW oscillations, where $\nu_s$ denotes a sterile neutrino. The ${\cal U}(1)$ symmetry ensures not only a light $\nu_s$ but also automatic `matter' parity.