# Proton Lifetime Upper Bound in Non-SUSY SU(5) GUT

## TL;DR

This paper establishes a theoretical upper bound on proton lifetime within non-SUSY SU(5) GUT models, considering specific light multiplet scenarios, aiding future experimental searches like Hyper-Kamiokande.

## Contribution

It derives criteria and performs numerical analysis to set testable upper bounds on proton lifetime in non-SUSY SU(5) GUTs with certain light multiplet assumptions.

## Key findings

- Certain light multiplets can significantly extend proton lifetime bounds.
- Numerical analysis provides concrete upper bounds for proton decay predictions.
- Results are relevant for upcoming nucleon decay experiments like Hyper-Kamiokande.

## Abstract

In preparation for upcoming nucleon decay searches at Hyper-Kamiokande, it is important to derive a theoretical upper bound on the proton lifetime in a general class of grand unified theory (GUT) models. In this paper, we make an attempt along this direction for non-SUSY SU(5) models, under the mild restrictions that only one or two SM-decomposed multiplets are singularly light, and that the SU(5) gauge theory is asymptotically free and thus there are no too large representations in the model. We derive criteria for SM-decomposed multiplets that potentially enhance the proton lifetime when they are singularly light. We perform a numerical analysis on the proton lifetime and show that some choices of singularly light multiplets can provide a testable upper bound on the proton lifetime.