Resonance search results from HPS and Future Prospects

The Heavy Photon Search (HPS) experiment at Jefferson Lab is searching for a new U(1) vector boson (``heavy photon'',``dark photon'' or A$^\prime$) in the mass range of 20-200 MeV/c$^2$. An A$^\prime$ in this mass range is theoretically favorable and may mediate dark matter interactions. In these models, the A$^\prime$ couples to the ordinary photon through kinetic mixing, which induces its coupling to electric charge. Since heavy photons couple to electrons, they can be produced through a process analogous to bremsstrahlung, subsequently decaying to an e+e− pair which can be observed as a narrow resonance above the dominant QED trident background. Using the CEBAF electron beam at Jefferson Lab incident on a thin tungsten target along with a compact, large acceptance forward spectrometer consisting of a silicon vertex tracker and lead tungstate electromagnetic calorimeter, HPS is accessing unexplored regions in the mass-coupling parameter space. The HPS engineering run took place in spring of 2015 using a 1.056 GeV, 50 nA beam and collected 1165 nb$^{−1}$ (7.29 mC) of data. This talk will present the first results of a resonance search for a heavy photon and prospects for future searches and detector upgrades.