Is charged lepton flavour violation a high energy phenomenon?

TL;DR

This paper explores a high-energy scenario where lepton flavor violation could be observable at colliders through right-handed neutrino production via a Z' portal, despite stringent low-energy constraints.

Contribution

It introduces a model where flavor violation at high energy can be detectable even with suppressed low-energy processes like mu --> e gamma.

Findings

High-energy lepton flavor violation signals can be observable at colliders.

Small flavor-violating couplings do not suppress the process rate at high energy.

The scenario circumvents traditional low-energy constraints on flavor violation.

Abstract

Searches for rare processes such as mu --> e gamma put stringent limits on lepton flavour violation expected in many Beyond the Standard Model physics scenarios. This usually precludes the observation of flavour violation at high energy colliders such as the LHC. We here discuss a scenario where right-handed neutrinos are produced via a Z' portal but which can only decay via small flavour violating couplings. Consequently, the process rate is unsuppressed by the small couplings and can be visible despite unobservably small mu --> e gamma rates.