Hunting for ALPs with Lepton Flavor Violation

TL;DR

This paper investigates how axion-like particles could cause lepton flavor violating decays, providing a general framework to analyze experimental data and explore connections to muon and electron g-2 anomalies.

Contribution

It develops a comprehensive effective Lagrangian approach to study ALP-induced LFV processes applicable to any ALP mass and coupling, and analyzes experimental constraints and future prospects.

Findings

Derived general expressions for ALP contributions to LFV decays.

Identified experimental patterns to test ALP effects.

Revisited ALP explanations for muon and electron g-2 discrepancies.

Abstract

We examine the low-energy signatures of axion-like particles (ALPs) in lepton flavor violating (LFV) processes. By using a dimension-5 effective Lagrangian, we compute the most general ALP contributions to LFV decays of leptons and mesons. The provided expressions are valid for any choice of ALP mass and couplings. We explore the complementarity of different processes, identifying specific patterns to be experimentally tested. Constraints on LFV couplings are derived from existing data and prospects for forthcoming experiments are also discussed. As a by-product, we revisit the possibility of a simultaneous explanation of the observed discrepancies in the muon and electron $g-2$ through ALP interactions.