Proton decay into charged leptons

TL;DR

This paper explores rare proton decay modes involving three leptons, which could dominate due to lepton-flavor symmetry conservation, and links these decays to high-energy physics and recent flavor anomalies.

Contribution

It introduces novel three-lepton proton decay channels mediated by high-dimensional operators, connecting proton decay to TeV-scale physics and flavor anomalies.

Findings

Certain three-lepton decay modes could be dominant.

Observation would probe energy scales around 100 TeV.

Models could explain B meson decay anomalies.

Abstract

We discuss proton and neutron decays involving three leptons in the final state. Some of these modes could constitute the dominant decay channel because they conserve lepton-flavor symmetries that are broken in all usually considered channels. This includes the particularly interesting and rarely discussed $p\to e^+ e^+ \mu^-$ and $p\to \mu^+ \mu^+ e^-$ modes. As the relevant effective operators arise at dimension 9 or 10, observation of a three-lepton mode would probe energy scales of order 100 TeV. This allows to connect proton decay to other probes such as rare meson decays or collider physics. UV completions of this scenario involving leptoquarks unavoidably violate lepton flavor universality and could provide an explanation to the recent $b\to s\mu\mu$ anomalies observed in $B$ meson decays.