DELight: when helium sweats over dark matter

In recent decades, astronomical and cosmological observations consistently reveal that most of the Universe's matter remains hidden to even the most sensitive telescopes due to its nonluminous nature—dark matter. Exploring dark matter particles has become a tantalizing pursuit in modern physics. New-generation direct search experiments aim at the observation of weak-scale dark matter particles in direct interactions within the target material, with successors already in planning. Simultaneously, a new era has begun for the direct detection of ever lighter dark matter candidates, leveraging novel detector designs with ultra-low detection thresholds. These advancements enable the exploration of new detection channels and unprecedentedly low dark matter masses. This presentation summarizes the state-of-the-art in direct light dark matter searches, including a community-wide challenge referred to as the “low energy excess”, and highlights a new project, DELight, which will take advantage of the unique properties of superfluid helium-4 to search for dark matter down to the sub-100MeV mass scale.