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Search for pair production of heavy top-like quarks decaying to a high-pT W boson and a b quark in the lepton plus jets final state at √s=7 TeV with the ATLAS detector

CollaborationWith : Abdelalim Aly, Ahmed Aly / Alexandre, Gauthier / Backes, Moritz / Barone, Gaetano / Bell, Paul / Bell, William / Benhar Noccioli, Eleonora / Blondel, Alain / Bucci, Francesca / Clark, Allan Geoffrey / Dao, Valerio / Doglioni, Caterina / Ferrere, Didier / Gadomski, Szymon / Gonzalez Sevilla, Sergio / Goulette, Marc / Iacobucci, Giuseppe / La Rosa, Alessandro / Lister, Alison / Martin Dit Latour, Bertrand / Mermod, Philippe / Mora Herrera, Maria Clemencia Rosario / Nektarijevic, Snezana / Nikolics, Katalin / Pasztor, Arpad / Picazio, Attilio / Pohl, Martin / Rosbach, Kilian / Rosselet, Laurent / Wu, Xin
Published in Physics Letters. B. 2013, vol. 718, no. 4-5, p. 1284-1302
Abstract A search is presented for production of a heavy up-type quark (t′) together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb−1 of pp collisions at √s=7 TeV recorded in 2011 with 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, large missing transverse momentum and at least three jets. The analysis strategy relies on the substantial boost of the W bosons in t′t′ signal when mt′≳400 GeV. No significant excess of events above the Standard Model expectation is observed and the result of the search is interpreted in the context of fourth-generation and vector-like quark models. Under the assumption of a branching ratio BR(t′→Wb)=1BR(t′→Wb)=1, a fourth-generation t′t′ quark with mass lower than 656 GeV656 GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass ∼126 GeV∼126 GeV at the LHC, upper limits are derived in the two-dimensional plane of BR(t′→Wb)BR(t′→Wb) versus BR(t′→Ht)BR(t′→Ht), where H is the Standard Model Higgs boson, for vector-like quarks of various masses.
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ATLAS COLLABORATION. Search for pair production of heavy top-like quarks decaying to a high-pT W boson and a b quark in the lepton plus jets final state at √s=7 TeV with the ATLAS detector. In: Physics Letters. B, 2013, vol. 718, n° 4-5, p. 1284-1302. https://archive-ouverte.unige.ch/unige:40040

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Deposited on : 2014-09-08

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