“Dark Matter Search Results from 4.2 Tonne − Years of Exposure of the LUX-ZEPLIN (LZ) Experiment” (2025), by J. Aalbers et al. Physics and Astronomy research paper. Original abstract below, unchanged. A free PDF is available.

Dark Matter Search Results from 4.2 Tonne − Years of Exposure of the LUX-ZEPLIN (LZ) Experiment

J. Aalbers, D. S. Akerib, A. K. Al Musalhi et al. · May 12, 2025 · Physics and Astronomy

Abstract

We report results of a search for nuclear recoils induced by weakly interacting massive particle (WIMP) dark matter using the LUX-ZEPLIN (LZ) two-phase xenon time projection chamber. This analysis uses a total exposure of 4.2±0.1 tonne-years from 280 live days of LZ operation, of which 3.3±0.1 tonne-years and 220 live days are new. A technique to actively tag background electronic recoils from ²¹⁴Pb β decays is featured for the first time. Enhanced electron-ion recombination is observed in two-neutrino double electron capture decays of ¹²⁴Xe, representing a noteworthy new background. After removal of artificial signal-like events injected into the dataset to mitigate analyzer bias, we find no evidence for an excess over expected backgrounds. World-leading constraints are placed on spin-independent (SI) and spin-dependent WIMP-nucleon cross sections for masses ≥9 GeV/c². The strongest SI exclusion set is 2.2×10⁻⁴⁸ cm² at the 90% confidence level and the best SI median sensitivity achieved is 5.1×10⁻⁴⁸ cm², both for a mass of 40 GeV/c².

Free PDF DOI: 10.1103/4dyc-z8zf