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Search for tt resonances in the lepton plus jets final state with ATLAS using 4.7  fb−1 of pp collisions at √s=7  TeV

CollaborationWith : Alexandre, Gauthier / Backes, Moritz / Barone, Gaetano / Bell, Paul / Bell, William / Benhar Noccioli, Eleonora / Bucci, Francesca / Clark, Allan Geoffrey / Doglioni, Caterina / Ferrere, Didier / Gadomski, Szymon / Gonzalez Sevilla, Sergio / Goulette, Marc / Iacobucci, Giuseppe / La Rosa, Alessandro / 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 Physical Review. D. 2013, vol. 88, no. 01, p. 012004
Abstract A search for new particles that decay into top quark pairs (tt) is performed with the ATLAS experiment at the LHC using an integrated luminosity of 4.7  fb−1 of proton–proton (pp) collision data collected at a center-of-mass energy s√=7  TeV. In the tt→WbWb decay, the lepton plus jets final state is used, where one W boson decays leptonically and the other hadronically. The tt system is reconstructed using both small-radius and large-radius jets, the latter being supplemented by a jet substructure analysis. A search for local excesses in the number of data events compared to the Standard Model expectation in the tt invariant mass spectrum is performed. No evidence for a tt resonance is found and 95% credibility-level limits on the production rate are determined for massive states predicted in two benchmark models. The upper limits on the cross section times branching ratio of a narrow Z′ resonance range from 5.1 pb for a boson mass of 0.5 TeV to 0.03 pb for a mass of 3 TeV. A narrow leptophobic topcolor Z′ resonance with a mass below 1.74 TeV is excluded. Limits are also derived for a broad color-octet resonance with Γ/m=15.3%. A Kaluza–Klein excitation of the gluon in a Randall–Sundrum model is excluded for masses below 2.07 TeV.
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ATLAS COLLABORATION. Search for tt resonances in the lepton plus jets final state with ATLAS using 4.7  fb−1 of pp collisions at √s=7  TeV. In: Physical Review. D, 2013, vol. 88, n° 01, p. 012004. https://archive-ouverte.unige.ch/unige:38939

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Deposited on : 2014-07-28

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