Contributions of axionlike particles to lepton dipole moments

Contributions of a spin-0 axionlike 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 longstanding muon g-2 discrepancy at the expense of relatively large ALP-γγ 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 potentially unveil a new source of $CP$ violation which could have far-reaching ramifications.