Direct detection of mirror helium dark matter in the CRESST-III experiment

Abstract

Within the context of mirror dark matter, the dominant mass component of the Milky Way dark halo consists of mirror helium ions. Mirror helium can interact with ordinary matter if the kinetic mixing interaction exists. Mirror helium being rather light, $m\simeq 3.73$ GeV, generally produces sub-keV recoils in direct detection experiments. Recently, the CRESST-III experiment has began probing the sub-keV recoil energy region and is currently the most sensitive probe of such particles. We point out here that the small excess seen in the low energy recoil data obtained in the CRESST-III experiment is consistent with mirror helium scattering if the kinetic mixing parameter is around $\hat{I}\mu \approx 5\times 10^{-10}$. This kinetic mixing strength lies within the estimated range favoured by small scale structure considerations.

5 pages