Orateur
Description
The XENONnT experiment, located at the INFN Laboratori Nazionali del Gran Sasso, is a multi-tonne dual-phase xenon time projection chamber designed primarily for the direct detection of WIMPs. While standard searches require both scintillation (S1) and ionization (S2) signals, an ionization-only (S2-only) analysis significantly lowers the energy threshold, extending sensitivity to sub-GeV dark matter (DM) and other light DM candidates.
This talk presents the latest results of a blinded search for light DM using S2-only data with a total exposure of 7.83 tonne-year. The first complete and generalizable S2-only background model for XENONnT is developed and validated. Dedicated background suppression techniques, including machine learning, mitigate instrumental backgrounds such as cathode radioactivity and delayed electrons. We report new limits on spin-independent DM-nucleon scattering for masses between 3 and 8 GeV/c2, excluding cross sections above 6.0 × 10-45 cm2 at a mass of 5 GeV/c2. Furthermore, we provide world-leading constraints on DM-electron scattering, axion-like particles, and dark photons. These results also push the sensitivity of liquid xenon detectors closer to the irreducible solar neutrino fog.