An SU(5)$\otimes$Z_{13} Grand Unification Model

TL;DR

This paper introduces an SU(5) grand unified model incorporating an invisible axion and a Z_{13} symmetry, achieving gauge coupling unification, proton stability, and protection of the axion from gravity effects.

Contribution

It presents a novel SU(5) GUT model with a Z_{13} symmetry that naturally stabilizes the proton and protects the axion, aligning with experimental coupling measurements.

Findings

Successful unification of gauge couplings at the GUT scale.

Proton stability ensured by Z_{13} symmetry and exotic fields.

Invisible axion protected from semi-classical gravity effects.

Abstract

We propose an SU(5) grand unified model with an invisible axion and the unification of the three coupling constants which is in agreement with the values, at $M_Z$, of $\alpha$, $\alpha_s$, and $\sin^2\theta_W$. A discrete, anomalous, $Z_{13}$ symmetry implies that the Peccei-Quinn symmetry is an automatic symmetry of the classical Lagrangian protecting, at the same time, the invisible axion against possible semi-classical gravity effects. Although the unification scale is of the order of the Peccei-Quinn scale the proton is stabilized by the fact that in this model the standard model fields form the SU(5) multiplets completed by new exotic fields and, also, because it is protected by the $Z_{13}$ symmetry.