Summary Report of the 721th WE-Heraeus-Seminar: Light Dark Matter Searches.

Dark matter is the name assigned to one of the most important contemporary challenges that fundamental physics research is facing. In recent years, the hypothesis that dark matter might be "light" is gaining interest. Following this idea, dark matter particles belong to a new, unexplored dark sector, that is communicating with the Standard Model through one (or more) dark mediator particles. The mass scale of such dark sector particles, i.e. the mediators and the stable dark matter particles, could be comparable to the proton mass or below. Light dark matter would be very difficult to detect with high-energy colliders or with direct detection experiments, so that accelerator-based dark matter searches with smaller, but dedicated experiments are important. The capabilities of high-intensity cw electron and proton beams enable unique opportunities for probing the dark sector. These experimental approaches are complementary to searches for dark matter at the high-energy frontier with the LHC at CERN. The aim of the workshop was to discuss light dark matter searches with national and international experts from experiments as well as from theory.