WISPy Cold Dark Matter

TL;DR

This paper explores how weakly interacting slim particles like ALPs and hidden photons could account for cold dark matter, highlighting their parameter space and potential for detection with current and future experiments.

Contribution

It identifies extensive parameter regions where ALPs and HPs can be dark matter and discusses their detectability with various experimental methods.

Findings

Large parameter space consistent with observed dark matter density

Many regions overlap with models of fundamental physics

Upcoming experiments can probe significant parts of this space

Abstract

Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches -- exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques -- can probe large parts of this parameter space in the foreseeable future.