Search for Dark Matter Particle Interactions with Electron Final States with DarkSide-50

Abstract

We present a search for dark matter particles with sub-$\mathrm{GeV}/{c}^{2}$ masses whose interactions have final state electrons using the DarkSide-50 experiment's $(12\text{ }306\ifmmode\pm\else\textpm\fi{}184)\text{ }\text{ }\mathrm{kg}\text{ }\mathrm{d}$ low-radioactivity liquid argon exposure. By analyzing the ionization signals, we exclude new parameter space for the dark matter-electron cross section ${\overline{\ensuremath{\sigma}}}_{e}$, the axioelectric coupling constant ${g}_{\mathrm{A}e}$, and the dark photon kinetic mixing parameter $\ensuremath{\kappa}$. We also set the first dark matter direct-detection constraints on the mixing angle ${|{U}_{e4}|}^{2}$ for $\mathrm{keV}/{c}^{2}$ sterile neutrinos.