Dark Matter with Axion-Like Particle Mediators

We study the cosmology and experimental signatures of a thermal dark matter (DM) freeze-out model where DM interacts with Standard Model (SM) particles via an axion-like particle (ALP). We calculate the DM abundance from annihilations into ALPs and SM gauge bosons, and we determine which masses and coupling constants produce the observed abundance of DM within the regime of validity of the effective field theory. We constrain the model using collider searches for ALPs and indirect detection bounds on DM annihilation to photons to determine the parameter space still unconstrained by experiment and help guide future searches for DM and ALPs.