Hitting two BSM particles with one lepton-jet: Search for a top partner decaying to a dark photon, resulting in a lepton-jet

A maverick top partner model, decaying to a dark photon was suggested in Ref. [1]. The dark photon decays to two overlapping electrons for dark photon masses of approximate to 100 MeV, and results in a so-called lepton-jet. The event includes a top quark as well, which results in events with two boosted objects, one heavy and the other light. We propose a search strategy exploiting the unique signal topology. We show that for a set of kinematic selections, both in hadronic and leptonic decay channel of the SM top quark, almost all background can be eliminated, leaving enough signal events up to top partner mass of about 3.5 TeV for the search to be viable at the LHC Run 2. Further, integrated luminosity needed for the proposed search to be sensitive is presented as a function of top partner mass.