We report on a search for dark matter particles interacting with xenon nuclei in an exposure of 2.84 tonne-years with the LUX-ZEPLIN (LZ) experiment. An extended nuclear recoil energy window up to approximately 270 keV enables searches for effective field theory and inelastic models of dark matter where high-energy recoils account for a larger fraction of the predicted recoil spectrum compared to the nominal spin independent interaction. We observe one event with characteristics consistent with a nuclear recoil of 248 ±23 (stat) ±23 (sys) keV, in a region where the known background expectation is low. A profile likelihood ratio test finds tension with the background-only hypothesis at a global significance of 2.6σ when accounting for look-elsewhere effects, with a maximum local significance of 3.4σ across the models tested. We describe the analysis and event of interest, the background model used in the statistical inference, and detail several of the rare background topologies considered.
Source : https://lz.lbl.gov/
