Search for dark matter particle interactions with electron final states with DarkSide-50

TL;DR

This paper reports a search for sub-GeV dark matter particles interacting with electrons using the DarkSide-50 liquid argon detector, setting new constraints on various dark matter models and parameters.

Contribution

It provides the first direct-detection constraints on keV sterile neutrino mixing angles and explores new parameter space for dark matter-electron interactions.

Findings

Excluded new parameter space for dark matter-electron cross section

Set constraints on axioelectric coupling constant and dark photon kinetic mixing

Provided first constraints on sterile neutrino mixing angle U_e4

Abstract

We present a search for dark matter particles with sub-GeV/$c^2$ masses whose interactions have final state electrons using the DarkSide-50 experiment's (12306 $\pm$ 184) kg d low-radioactivity liquid argon exposure. By analyzing the ionization signals, we exclude new parameter space for the dark matter-electron cross section $\bar{\sigma}_e$, the axioelectric coupling constant $g_{Ae}$, and the dark photon kinetic mixing parameter $\kappa$. We also set the first dark matter direct-detection constraints on the mixing angle $\left|U_{e4}\right|^2$ for keV sterile neutrinos.