Exploring muonphilic ALPs at $μ^+μ^-$ and $μp$ colliders

Abstract

Axion-like particles (ALPs) are new particles that extend beyond the standard model (SM) and are highly motivated. When considering ALPs within an effective field theory, their couplings with SM particles can be studied independently. It is a daunting task to search for GeV-scale ALPs coupled to muons in collider experiments because their coupling is proportional to the muon mass.However, a recent study by Altmannshofer, Dror, and Gori (2022) highlighted the importance of a four-point interaction, W -µ-ν µ -a, which coupling is not dependent on the muon mass. This interaction provides a new opportunity to explore muonphilic ALPs (µALPs) at the GeV scale.We concentrate on µALPs generated through this four-point interaction at future µ + µ − and µp colliders that subsequently decay into a pair of muons. This new channel for exploring µALPs with 1 GeV ≤ m a M W can result in much stronger future constraints than the existing ones.