Title:
New constraints on WIMP dark matter from the LUX-ZEPLIN (LZ) experiment
Abstract:
Dark matter detection experiments based on liquid xenon time projection chambers have been steadily increasing in sensitivity to the weakly interacting massive particle (WIMP) over the past two decades. The LZ experiment, employing a two-phase xenon time projection chamber (TPC) containing 7 tonnes of liquid xenon, leads the way. Recently, the collaboration released new results from a combined analysis using data from the 2022 and 2024 science campaigns, amounting to a live exposure of 4.2 tonne-years. No evidence for an excess over expected backgrounds was found across all the test WIMP masses. The resulting limit on the spin-independent WIMP-nucleon cross, world-leading for masses above 9 GeV/c2, surpasses previous best limits by about a factor of four. In this talk, I will describe the new results---including a new technique to actively tag background electronic recoils from Pb-214 beta decays, the observation of charge-suppressed two-neutrino double electron capture events from Xe-124 decays, and the bias mitigation technique called "salting"---and sketch out what is in the horizon for liquid xenon TPC searches.
