Special HEP-Astro Seminar | Search for Dark Matter Interactions at High Recoil Energy with the LUX-ZEPLIN Experiment

The LUX-ZEPLIN (LZ) experiment is a dual-phase xenon time projection chamber designed to search for dark matter interactions with unprecedented sensitivity. While conventional WIMP searches focus primarily on low-energy nuclear recoils, a broader class of dark matter models can produce significant signals at much higher recoil energies. In a new search using 2.84 tonne-years of LZ exposure, we extend the nuclear-recoil energy window to approximately 270 keV to probe momentum- and velocity-dependent interactions described by non-relativistic effective field theory, as well as inelastic dark matter models. The search observes one event in a region of low expected background, consistent with a 248 • /- 23 (stat) /- 23 (sys) keVnr nuclear recoil. I will describe the motivation, methodology, and results of this extended-energy search, including the investigation of the high-energy event and possible background interpretations. I will also highlight work carried out at the University of Michigan that helped enable the extension to high recoil energies, particularly the calibration and detector-response modeling of electronic and nuclear recoils, together with studies of backgrounds relevant to the expanded search region.