Charged Higgs Probes of Dark Bosons at the LHC

A very light (GeV scale) dark gauge boson ($Z'$) is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the $3.6 \sigma$ deviation in the muon $g$-2 measurement. We suggest top quark decays as a venue to search for light dark force carriers at the LHC. Such $Z'$s can be easily boosted, and they can decay into highly collimated leptons (lepton-jet) with large branching ratio. We investigate a scenario where a top quark decays to $b W$ accompanied by one or multiple dark force carriers and find that such a scenario could be easily probed at the early stage of LHC Run 2.