Abstract
Abstract:
A search is presented for the pair production of heavy vector-like B quarks, primarily targeting
B quark decays into a W boson and a top quark. The search is based on 36.1 fb−1 of pp
collisions at √s = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN
Large Hadron Collider. Data are analysed in the lepton-plus-jets final state, characterised by a
high-transverse-momentum isolated electron or muon, large missing transverse momentum, and multiple
jets, of which at least one is b-tagged. No significant deviation from the Standard Model
expectation is observed. The 95% confidence level lower limit on the B mass is 1350 GeV assuming a
100% branching ratio to Wt. In the SU(2) singlet scenario, the lower mass limit is 1170 GeV. This
search is also sensitive to a heavy vector-like B quark decaying into other final states (Z b and
Hb) and thus mass limits on B production are set as a function of the decay branching ratios. The
100% branching ratio limits are found to be also applicable to heavy vector-like X production, with
charge +5/3, that decay into Wt.