A search is presented for production of a heavy up-type quark (t') together with its antiparticle, assuming subsequent decay to a W boson and a b quark, t'(t) over bar' -> W(+)bW(-)(b) over bar. The search is based on 1.04 fb(-1) of proton-proton collisions at root s = 7 TeV collected by the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton + jets final state, characterized by a high transverse momentum isolated electron or muon, high missing transverse momentum, and at least three jets. No significant excess of events above the background expectation is observed. A 95% C.L. lower limit of 404 GeV is set for the mass of the t' quark. RI Gutierrez, Phillip/C-1161-2011; Fazio, Salvatore /G-5156-2010; Pacheco Pages, Andres/C-5353-2011; Moorhead, Gareth/B-6634-2009; Livan, Michele/D-7531-2012; Alexa, Calin/F-6345-2010; Takai, Helio/C-3301-2012; Doyle, Anthony/C-5889-2009; semprini cesari, nicola/G-7817-2012; Petrucci, Fabrizio/G-8348-2012; Smirnov, Sergei/F-1014-2011; Wemans, Andre/A-6738-2012; Jones, Roger/H-5578-2011; Ferrando, James/A-9192-2012; Fabbri, Laura/H-3442-2012; Villa, Mauro/C-9883-2009; Delmastro, Marco/I-5599-2012

Search for Pair Production of a Heavy Up-Type Quark Decaying to a W Boson and a b Quark in the lepton plus jets Channel with the ATLAS Detector