First Direct Detection Limits on sub-GeV Dark Matter from XENON10

TL;DR

This paper reports the first direct detection limits on sub-GeV dark matter using XENON10 data, demonstrating sensitivity to dark matter particles as light as 20 MeV through electron scattering events.

Contribution

It presents the first limits on dark matter-electron scattering for dark matter in the MeV to GeV range using a direct detection experiment.

Findings

Set limits on dark-matter-electron cross section down to 3 x 10^{-38} cm^2 at 100 MeV

Bound dark matter masses between 20 MeV and 1 GeV with cross sections below 10^{-37} cm^2

Proved direct detection experiments can probe sub-GeV dark matter candidates

Abstract

The first direct detection limits on dark matter in the MeV to GeV mass range are presented, using XENON10 data. Such light dark matter can scatter with electrons, causing ionization of atoms in a detector target material and leading to single- or few-electron events. We use 15 kg-days of data acquired in 2006 to set limits on the dark-matter-electron scattering cross section. The strongest bound is obtained at 100 MeV where sigma_e < 3 x 10^{-38} cm^2 at 90% CL, while dark matter masses between 20 MeV and 1 GeV are bounded by sigma_e < 10^{-37} cm^2 at 90% CL. This analysis provides a first proof-of-principle that direct detection experiments can be sensitive to dark matter candidates with masses well below the GeV scale.