A Leptonic ALP Portal to the Dark Sector

TL;DR

This paper explores a leptonic axion-like particle (ALP) model linking anomalies in magnetic moments to dark matter, with specific predictions testable by upcoming experiments.

Contribution

It introduces a leptonic ALP portal model connecting magnetic moment anomalies to dark matter, analyzing experimental constraints and future testability.

Findings

ALP contributes to muon and electron g-2 via 2-loop diagrams

Dark matter relic abundance from p-wave annihilation to ALPs

Parameter space is tightly constrained but testable soon

Abstract

We discuss the leptonic ALP portal as a simple scenario that connects observed discrepancies in anomalous magnetic moments to the Dark Matter relic abundance. In this framework an axion-like particle in the multi-MeV range couples to SM leptons and a DM fermion, with mass above the ALP mass but below a GeV. The ALP contributes to $(g-2)_\mu$ and $(g-2)_e$ dominantly through 2-loop Barr-Zee diagrams, while the DM abundance is generated by $p$-wave annihilation to ALP pairs. Constraints from beam-dump experiments, colliders and CMB probes are very stringent, and restrict the viable parameter space to a rather narrow region that will be tested in the near future.