High Energy Physics Seminar
A new frontier in the search for dark matter is based on the idea of detecting the decoherence caused by dark matter scattering against a mesoscopic superposition of normal matter. Such superpositions are uniquely sensitive to very small momentum transfers from new particles and forces, especially dark matter with a mass below 100 MeV. Here we investigate what sorts of dark sectors are inaccessible with existing methods but would induce noticeable decoherence in the next generation of matter interferometers. We show that very weak, but medium range (0.1 nm - 1 μm) elastic interactions between matter and dark matter are particularly suitable. We construct toy models for such interactions, discuss existing constraints, and delineate the expected sensitivity of forthcoming experiments. The first hints of dark matter in these devices would appear as variations in the anomalous decoherence rate with a period of one sidereal day. This is a generic signature of interstellar sources of decoherence, clearly distinguishing it from terrestrial backgrounds. The OTIMA experiment under development in Vienna will probe a narrow class of dark matter models, while the aggressive proposals of the MAQRO collaboration and Pino et al. would open up many orders of magnitude in dark matter mass, interaction range, and coupling strength.