Searches for Vector Like Quarks Decaying to Ht, Zt, or Wt in the Single Lepton Channel with the ATLAS Detector

Abstract

A search for single production of Vector-Like quarks decaying to the Higgs boson and a top quark, or a massive vector boson and a top quark is presented. Events with exactly one high momentum lepton, at least three hadronic jets, of which at least one originates from a b-quark, and large missing transverse energy are selected. Data was collected from proton-proton collisions at center of mass energy sqrt(s)=13 TeV and integrated luminosity of 139 fb -1 representing the full LHC Run 2 dataset, using the ATLAS detector. This search uses the event effective mass as a discriminating variable in a binned maximum likelihood fit. No significant excess of events is observed in the data above predicted background. Exclusion limits on the signal production cross section are set at 95% confidence level, extending the exclusion limits to masses of 1.9 TeV for singlet T models of Vector-Like quarks, with universal coupling strength κ > 0.6. These results also exclude single production of the exotically charged X^5/3 Vector-Like quark at a mass of 1.5 TeV for coupling κ = 0.5. We also present a study of jet charge in searches for high mass exotically charged particles. We expect little benefit from use of jet charge as studied here, but expect that future work can extract more value.