DARWIN/XLZD: a future xenon observatory for dark matter and other rare interactions

The DARWIN/XLZD experiment is a next-generation dark matter detector with a multi-ten-ton liquid xenon time projection chamber at its core. Its principal goal will be to explore the experimentally accessible parameter space for Weakly Interacting Massive Particles (WIMPs) in a wide mass-range, until interactions of astrophysical neutrinos will become an irreducible background. The prompt scintillation light and the charge signals induced by particle interactions in the liquid xenon target will be observed by VUV-sensitive, ultra-low background photosensors. Besides its excellent sensitivity to WIMPs with masses above $\sim$5\,GeV, such a detector with its large mass, low-energy threshold and ultra-low background level will also be sensitive to other rare interactions, and in particular also to bosonic dark matter candidates with masses at the keV-scale. We present the detector concept, discuss the main sources of backgrounds, the technological challenges and some of the ongoing detector design and R&D efforts, as well as the large-scale demonstrators. We end by discussing the sensitivity to particle dark matter interactions.