Leveraging Unique Methods to Investigate Near-target dArk matter

Ordinary matter — stars, planets, the stuff we are made from — accounts for only 5% of the universe. The remainder of the universe is made of dark matter and dark energy. Although we infer dark matter due to its gravitational pull, we have not yet observed it having any interactions with the Standard Model. If such interactions exist, then they must be incredibly weak, else we would have detected them. Confirming the existence of dark matter would transform our understanding of physics, from the smallest particles to the largest cosmological structures. Accelerator-based liquid argon time projection chamber (LArTPC) neutrino detectors provide a unique avenue to search for cosmologically-motivated sub-GeV dark matter mass range - an area not accessible to other searches. The production of high-intensity neutrino beams involves a very high number of particle interactions, providing a fantastic environment in which to search for dark matter particles that interact very weakly with Standard Model forces. This project will use the highly performant Short Baseline Near Detector (SBND) with its low noise readout, and excellent photon detection system to perform its first accelerator-based LArTPC search for cosmologically-motivated sub-GeV dark matter. By combining nanosecond timing with novel reconstruction of low-energy “blip” events, SBND will probe a WIMPLess-based model with discovery potential or world-leading limits in an area relevant to the cosmological relic density. The same capabilities will also enhance SBND’s neutrino programme, where precision timing is critical for separating overlapping interactions and improving background rejection. This project is exceptionally timely. With SBND now taking data, there is a unique opportunity to develop and optimise photon- and low energy-based tools on real events and to have them ready for the next-generation LArTPC, DUNE.