Search for single-production of vector-like quarks decaying into Wb in the fully hadronic final state in pp collisions at √s = 13 TeV with the ATLAS detector

Abstract

A search for T and Y vector-like quarks produced in proton-proton collisions ata centre-of-mass energy of 13TeV and decaying into Wb in the fully hadronic final state ispresented. The search uses 139 fb-1 of data collected by the ATLAS detector at the LHCfrom 2015 to 2018. The final state is characterised by a hadronically decaying W boson withlarge Lorentz boost and a b-tagged jet, which are used to reconstruct the invariant mass ofthe vector-like quark candidate. The main background is QCD multijet production, whichis estimated using a data-driven method. Upon finding no significant excess in data, masslimits at 95% confidence level are obtained as a function of the global coupling parameter,κ. The observed lower limits on the masses of Y quarks with κ = 0.5 and κ = 0.7 are2.0TeV and 2.4TeV, respectively. For T quarks, the observed mass limits are 1.4TeV forκ = 0.5 and 1.9TeV for κ = 0.7.