Exploring the Role of Axions and Other WISPs in the Dark Universe

TL;DR

This paper reviews the theoretical motivation and experimental efforts to detect axions and WISPs as potential non-thermal dark matter candidates, highlighting their parameter space and ongoing searches.

Contribution

It provides a comprehensive overview of the phenomenology, parameter space, and experimental approaches related to axions and WISPs in the context of dark matter.

Findings

Large parameter space can account for dark matter abundance

Multiple experimental methods can probe significant regions of this space

Future experiments are poised to explore key areas of WISP parameter space

Abstract

Axions and other very weakly interacting slim particles (WISPs) may be non-thermally produced in the early universe and survive as constituents of the dark universe. We describe their theoretical motivation and their phenomenology. A huge region in parameter space spanned by their couplings to photons and their masses can give rise to the observed cold dark matter abundance. A wide range of experiments - direct dark matter searches exploiting microwave cavities, searches for solar axions or WISPs, and light-shining-through-a-wall searches - can probe large parts of this parameter space in the foreseeable future.