Proton Stability in $SU(5)\times U(1)$ and $SU(6)\times SU(2)$ GUTs

TL;DR

This paper explores specific grand unified theories based on flipped SU(5)×U(1) and SU(6)×SU(2) groups, demonstrating how their structure suppresses proton decay operators and analyzing their phenomenological viability.

Contribution

It introduces explicit models with matter placement that suppresses gauge-mediated proton decay, providing a detailed theoretical and phenomenological analysis.

Findings

Proton decay operators are suppressed at leading order in the models.

The models' spectra are viable with respect to current phenomenological constraints.

Other operators may contribute significantly to proton decay rates.

Abstract

We consider explicit unified models based on the flipped ${SU(5)\times U(1)}$ and $SU(6)\times SU(2)$ gauge groups in which gauge mediated proton decay operators are suppressed at leading order due to the special placement of matter fields in unified multiplets. We discuss both the theoretical structure and phenomenological implications of these models. For the latter, we examine the viability of the physical spectrum in each scenario and focus on the possible presence of other operators that could also contribute significantly to the proton decay rate.