Selection rules for charged lepton flavour violating processes from residual flavour groups

TL;DR

This paper explores how residual flavour symmetries in the charged lepton sector influence observable lepton flavour violating processes, providing a framework to interpret current bounds and future experimental sensitivities.

Contribution

It systematically classifies residual flavour group effects in charged leptons and derives distinctive patterns for lepton flavour violation in effective field theory.

Findings

Distinctive patterns of lepton flavour violation are predicted.

Current bounds and future sensitivities are analyzed.

Searches for tau decays and muonium conversion are particularly powerful.

Abstract

We systematically investigate the possible phenomenological impact of residual flavour groups in the charged lepton sector. We consider all possible flavour charge assignments for abelian residual symmetries up to Z8. The allowed flavour structures of operators in Standard Model Effective Field Theory (up to dimension six) lead to distinctive and observable patterns of charged lepton flavour violating processes. We illustrate the relevance of such selection rules displaying the current bounds on and the future sensitivities to the new physics scale. These results demonstrate, in particular, the importance and discriminating power of searches for lepton flavour violating tau lepton decays and muonium to antimuonium conversion.