Contributions of axion-like particles to lepton dipole moments

TL;DR

This paper investigates how axion-like particles could explain the muon g-2 anomaly and affect lepton electric dipole moments, discussing experimental constraints and future tests for these particles.

Contribution

It analyzes the impact of light pseudoscalar ALPs on lepton dipole moments, highlighting their potential to resolve the muon g-2 discrepancy and exploring experimental constraints.

Findings

ALPs can resolve the muon g-2 discrepancy with large ALP-gamma gamma couplings.

Electron EDM measurements can probe smaller ALP interactions and CP violation.

Future electron EDM experiments could constrain or reveal new ALP physics.

Abstract

Contributions of a spin 0 axion-like particle (ALP) to lepton dipole moments, g-2 and EDMs, are examined. Barr-Zee and light-by-light loop effects from a light pseudoscalar ALP are found to be capable of resolving the long-standing muon g-2 discrepancy at the expense of relatively large ALP-gammagamma couplings. The compatibility of such large couplings with direct experimental constraints and perturbative unitarity bounds is discussed. Future tests of such a scenario are described. For CP violating ALP couplings, the electron EDM is found to probe much smaller, theoretically more easily accommodated ALP interactions. Future planned improvement in electron EDM searches is advocated as a way to not only significantly constrain ALP parameters but also, to potentially unveil a new source of CP violation which could have far reaching ramifications.