# New constraints and discovery potential of sub-GeV dark matter with xenon detectors

## TL;DR

This paper demonstrates that xenon detectors like LUX and LZ significantly improve constraints on sub-GeV dark matter detection, offering enhanced sensitivity and the potential for mass reconstruction of light DM particles.

## Contribution

The study introduces new constraints from LUX and LZ on sub-GeV dark matter, surpassing previous limits and highlighting their discovery potential.

## Key findings

- LUX constraints are three orders of magnitude more stringent than previous xenon experiments.
- LUX and LZ can distinguish signal from background using photon emission, enabling unambiguous detection.
- LZ can reconstruct DM mass with 20% accuracy for particles below 0.5 GeV.

## Abstract

Existing xenon dark matter (DM) direct detection experiments can probe the DM-nucleon interaction of DM with a sub-GeV mass through a search for photon emission from the recoiling xenon atom. We show that LUX's constraints on sub-GeV DM, which utilise the scintillation (S1) and ionisation (S2) signals, are approximately three orders of magnitude more stringent than previous xenon constraints in this mass range, derived from the XENON10 and XENON100 S2-only searches. The new LUX constraints provide the most stringent direct detection constraints for DM particles with a mass below 0.5 GeV. In addition, the photon emission signal in LUX and its successor LZ maintain the discrimination between background and signal events so that an unambiguous discovery of sub-GeV DM is possible. We show that LZ has the potential to reconstruct the DM mass with 20% accuracy for particles lighter than 0.5 GeV.