From Resonant to Broadband Searches for WISPy Cold Dark Matter

TL;DR

This paper explores the relationship between resonant and broadband detection methods for WISPy cold dark matter, analyzing how cavity size influences sensitivity and enabling more effective searches for axions and hidden photons.

Contribution

It clarifies the connection between resonant cavity and broadband detection setups, providing insights into sensitivity limits for large-scale off-resonance cavity experiments.

Findings

Transition from resonant to broadband detection modes analyzed

Sensitivity estimates for large cavities beyond photon wavelength derived

Guidelines for optimizing cavity-based dark matter searches established

Abstract

Dark matter may consist of light, very weakly interacting bosons, produced non-thermally in the early Universe. Prominent examples of such very weakly interacting slim particles (WISPs) are axions and hidden photons. Direct detection experiments for such particles are based on the conversion of these particles into photons. This can be done in resonant cavities, featuring a resonant enhancement, or by using suitably shaped reflecting surfaces that allow for broadband searches. In this note we want to elucidate the relation between the two setups and study the transition from resonant to broadband searches. This then allows to determine the sensitivity of off-resonance cavity searches for cavities much larger than the wavelength of the generated photons.