String-Inspired Special Grand Unification

TL;DR

This paper proposes a novel grand unified theory based on an $SO(32)$ gauge group in six dimensions, successfully embedding Standard Model fermions and canceling anomalies without exotic particles.

Contribution

It introduces a string-inspired $SO(32)$ GUT model on a 6D orbifold that naturally incorporates three generations and anomaly cancellation without additional exotic fermions.

Findings

All gauge anomalies canceled in the model

Standard Model fermions embedded in 6D bulk Weyl fermions

No exotic chiral fermions required at low energies

Abstract

We discuss a grand unified theory (GUT) based on an $SO(32)$ GUT gauge group broken to its subgroups including a special subgroup. In the $SO(32)$ GUT on six-dimensional (6D) orbifold space $M^4\times T^2/\mathbb{Z}_2$, one generation of the SM fermions can be embedded into a 6D bulk Weyl fermion in the $SO(32)$ vector representation. We show that for a three generation model, all the 6D and 4D gauge anomalies in the bulk and on the fixed points are canceled out without exotic chiral fermions at low energies.