Dark Photon Phenomenology

The dark photon, a non-Abelian U(1) gauge boson, is part of a system of dark matter particles called the dark sector. Dark photons can interact weakly with the Standard Model via kinetic mixing, allowing the dark photon to decay to an even multiplicity of leptons. Two possible production mechanisms exist: the SUSY portal or the Higgs portal. The generated SUSY particle or non-SM Higgs, respectively, decays to a dark particle, which then generates a cascade decay of dark photons. These dark photons are highly boosted and will decay to lepton jets—a highly collimated opposite-sign pair of leptons. ATLAS previously did a search for prompt lepton-jets in proton-proton collisions, but found no statistically significant deviation from Standard Model predictions. However, this ATLAS paper didn’t take pion contamination into account, which is a major issue when distinguishing between lepton jets and QCD jets. We received access to the source code from another search, which had accounted for hadron contamination by looking at 19 different possible decay channels. Using these 19 decay channels will allow us to do a more comprehensive search for dark photons that properly models showering and hadron contamination