Search for sub-GeV dark matter by annual modulation using XMASS-I detector

TL;DR

This paper reports on a search for sub-GeV and multi-GeV dark matter using the XMASS-I detector, setting new upper limits on interaction cross sections and exploring bremsstrahlung effects for the first time.

Contribution

It introduces the first experimental search for dark matter mediated by bremsstrahlung emission and extends the analysis to lower energy thresholds for multi-GeV dark matter.

Findings

No significant annual modulation signal was observed.

Set upper limits of $1.6 imes 10^{-33}$ cm$^2$ at 0.5 GeV for DM-nucleon cross section.

Established new constraints on dark matter interactions in the sub-GeV and multi-GeV mass ranges.

Abstract

A search for dark matter (DM) with mass in the sub-GeV region (0.32-1 GeV) was conducted by looking for an annual modulation signal in XMASS, a single-phase liquid xenon detector. Inelastic nuclear scattering accompanied by bremsstrahlung emission was used to search down to an electron equivalent energy of 1 keV. The data used had a live time of 2.8 years (3.5 years in calendar time), resulting in a total exposure of 2.38 ton-years. No significant modulation signal was observed and 90% confidence level upper limits of $1.6 \times 10^{-33}$ cm$^2$ at 0.5 GeV was set for the DM-nucleon cross section. This is the first experimental result of a search for DM mediated by the bremsstrahlung effect. In addition, a search for DM with mass in the multi-GeV region (4-20 GeV) was conducted with a lower energy threshold than previous analysis of XMASS. Elastic nuclear scattering was used to search down to a nuclear recoil equivalent energy of 2.3 keV, and upper limits of 2.9 $\times$10$^{-42}$ cm$^2$ at 8 GeV was obtained.