Search for pair produced new heavy quarks in proton-proton collisions with the ATLAS detector at the LHC

A search is presented for the pair production of a new heavy quark, T, assuming that it has a significant branching ratio to decay into a W boson and a light-flavor quark, q. The search is based on the 20 inverse fb of proton-proton collision data at $\sqrt{s}= 8$ TeV recorded in 2012-2013 with the ATLAS detector at the Large Hadron Collider. Data are analyzed in the lepton+jets channel, which is characterized by a high transverse momentum electron or muon, large missing transverse momentum, and at least four jets. The analysis strategy relies on the substantial momentum transferred to all of the decay products of the heavy quark. No significant excess above the Standard Model expectation is observed and 95% confidence level upper limits are derived on the cross section times the branching ratio of T quark in the lepton+jets channel.