Speaker
Description
Recent experimental advances now severely constrain electroweak-scale WIMPs produced via
thermal freeze-out, leading to a shift away from this standard paradigm. Here we consider
an axion-like particle (ALP), the pseudo-Goldstone boson of an approximate U(1) global
symmetry spontaneously broken at a high scale fa, as a mediator between the Standard
model (SM) particles and the dark matter (DM) particles. We explore the case where the
couplings are too small to allow for DM generation via freeze-out and the mediator particle
and the DM constitute a hidden sector which is thermally decoupled from the SM particles.
However, alternative generation mechanisms such as freeze-in and freeze-out from a decoupled
dark sector are now appropriate. Having determined the region of parameter space where
the correct relic density is obtained, we then revisit experimental constraints on ALPs from
electron beam dump experiments, astrophysics and rare B and K decays.
