High Energy Physics Seminars

The overwhelming evidence for dark matter (DM) in cosmological observations, manifested by its gravitational interactions, has inspired a major experimental effort to uncover its particle nature. The LHC, as well as direct and indirect detection experiments, have significantly constrained one of the best-motivated weak-scale DM models (WIMPs as dark matter candidates). In contrast, scenarios involving a light hidden sector dark matter with mediators in the MeV-GeV range has garnered a good deal of attention. Models with a hidden U(1) gauge symmetry, with a "dark" or "hidden sector" photons, are particularly attractive as they can be tested experimentally. If they exist, dark or heavy photons mix with ordinary photons through kinetic mixing, which induces their weak coupling to electrons, ∈e. Since they couple to electrons, heavy photons are radiated in electron scattering and can subsequently decay into e⁺e^-. Experiments at Jefferson Lab use these features to search for heavy photons in the mass range of 20 MeV/c2 to 500 MeV/c2 and couplings of ∈² > 10 ^-10 .

In this talk, I will summarize the experimental program for dark photon searches at Jefferson Lab. Results from the experiments that already took data, APEX and HPS, will be discussed together with plans for future measurements.