Constraints on Light Dark Matter Particles Interacting with Electrons from DAMIC at SNOLAB

Abstract

We report direct-detection constraints on light dark matter particles interacting with electrons. The results are based on a method that exploits the extremely low levels of leakage current of the DAMIC detector at SNOLAB of $2--6\ifmmode\times\else\texttimes\fi{}{{10}^{\ensuremath{-}22}\text{ }\text{ }\mathrm{A}\text{ }\mathrm{cm}}^{\ensuremath{-}2}$. We evaluate the charge distribution of pixels that collect $<10{e}^{\ensuremath{-}}$ for contributions beyond the leakage current that may be attributed to dark matter interactions. Constraints are placed on so-far unexplored parameter space for dark matter masses between 0.6 and $100\text{ }\text{ }\mathrm{MeV}\text{ }{c}^{\ensuremath{-}2}$. We also present new constraints on hidden-photon dark matter with masses in the range $1.2--30\text{ }\text{ }\mathrm{eV}\text{ }{c}^{\ensuremath{-}2}$.