New low-mass WIMP limit from XENON1T

The world's most sensitive dark matter detector to-date improves upon its own results below masses of ~12 GeV/c².

The new XENON1T result.

The XENON collaboration published a new study with a lower detector threshold which was achieved by reducing the coincidence requirement to two (=only two PMTs need to fire at the same time to treat this as a valid signal). One of the goals of the study was to search for signals from solar ⁸B-neutrinos scattering coherently off xenon nuclei. This process represents the 'ultimate' background for direct WIMP searches since it is indistinguishable from a dark matter WIMP signal.

The search for ⁸B neutrinos ended up without a signal above the background expectation, however, the same search allowed further constraining WIMP-nucleon interactions as well. Between 3 and 12 GeV/c², the new exclusion limit supersedes the previous XENON1T results from a similar analysis with a 3-fold coincidence level and from an analysis of charge-signals only.

Reference:
Search for Coherent Elastic Scattering of Solar 8B Neutrinos in the XENON1T Dark Matter Experiment
E. Aprile et al. (XENON)
Phys. Rev. Lett. 126, 091301 (2021), arxiv:2012.02846