Cryogenic resonant microwave cavity searches for hidden sector photons

Understand

The hidden sector photon is a weakly interacting hypothetical particle with sub-eV mass that kinetically mixes with the photon.

• We describe a microwave frequency light shining through a wall experiment where a cryogenic resonant microwave cavity is used to try and detect photons that have passed through an impenetrable barrier, a process only possible via mixing with hidden sector photons.
• For a hidden sector photon mass of 53 $\mu$eV we limit the hidden photon kinetic mixing parameter $\chi < 1.7\times10^{-7}$, which is an order of magnitude lower than previous bounds derived from cavity experiments in the same mass range.
• In addition, we use the cryogenic detector cavity to place new limits on the kinetic mixing parameter for hidden sector photons as a form of cold dark matter.