Grand Unification without Proton Decay

TL;DR

This paper presents a class of grand unified theories (GUTs) that do not predict proton decay, challenging the common belief that GUTs necessarily lead to proton decay due to gauge boson exchange.

Contribution

It introduces a class of GUTs where dimension 6 proton decay operators are absent, including many string and supergravity models.

Findings

Certain GUTs lack proton decay operators

Many string and supergravity models are in this class

Proton decay predictions can be avoided in these models

Abstract

It is commonly believed that grand unified theories (GUTs) predict proton decay. This is because the exchange of extra GUT gauge bosons gives rise to dimension 6 proton decay operators. We show that there exists a class of GUTs in which these operators are absent. Many string and supergravity models in the literature belong to this class.