# Proton decay at 1-loop

## TL;DR

This paper systematically analyzes one-loop ultraviolet completions of dimension-6 operators responsible for proton decay in the Standard Model effective theory, identifying two classes of models with distinct phenomenological implications.

## Contribution

It provides a comprehensive list of one-loop UV completions of proton decay operators and classifies models based on symmetry requirements and phenomenological features.

## Key findings

- Two classes of models: one with additional symmetry and dark matter candidate.
- Loop contributions can dominate proton decay without extra symmetries.
- Potential links to neutrino masses, LHC searches, and dark matter.

## Abstract

Proton decay is usually discussed in the context of grand unified theories. However, as is well-known, in the standard model effective theory proton decay appears in the form of higher dimensional non-renormalizable operators. Here, we study systematically the 1-loop decomposition of the $d=6$ $B+L$ violating operators. We exhaustively list the possible 1-loop ultra-violet completions of these operators and discuss that, in general, two distinct classes of models appear. Models in the first class need an additional symmetry in order to avoid tree-level proton decay. These models necessarily contain a neutral particle, which could act as a dark matter candidate. For models in the second class the loop contribution dominates automatically over the tree-level proton decay, without the need for additional symmetries. We also discuss possible phenomenology of two example models, one from each class, and their possible connections to neutrino masses, LHC searches and dark matter.