The Heavy Photon Search Experiment: Searching for Dark Photons at Jefferson Lab

The Heavy Photon Search (HPS) is new experiment at Jefferson Lab (JLab), which will search for massive vector gauge bosons (heavy/dark photons) in the mass range of 20-1000 MeV/c$^2$. These dark photons are expected on very general theoretical grounds and are motivated by recent astrophysical evidence suggesting they may mediate dark matter annihilations and/or interactions with ordinary matter. The dark photon couples to the ordinary photon through kinetic mixing which induces their weak coupling to electrons. This allows for dark photon production through a process analogous to bremsstrahlung radiation. If the coupling is large enough, the subsequent decay to $e^+e^-$ will produce a narrow peak in the $e^+e^-$ mass spectrum which can be observed above the dominant QED trident background. If the coupling is small enough, then the dark photons will travel detectable distances before decaying, providing a second signature. Using JLab's high luminosity electron beam along with a compact large acceptance forward spectrometer, silicon vertex tracker, PbWO$_4$ electromagnetic calorimeter and a muon detector, HPS will explore a large domain in the mass/coupling plane with extraordinary sensitivity. In this talk, I will discuss the status of the HPS experiment.