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 the t ̄ t signal when m t 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 ) = 1, a fourth-generation t quark with mass lower than 656 GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass ∼ 126 GeV at the LHC, upper limits are derived in the two-dimensional plane of BR ( t → Wb ) versus BR ( t → Ht ) ,where H is the Standard Model Higgs boson, for vector-like quarks of various masses

G. Aad, T. Abajyan, B. Abbott, J. Abdallah, S. Abdel Khalek, A.A. Abdelalim, et al. (2013). Search for pair production of heavy top-like quarks decaying to a high- W boson and a b quark in the lepton plus jets final state at with the ATLAS detector. PHYSICS LETTERS. SECTION B, 718, 1284-1302 [10.1016/j.physletb.2012.11.071].

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

BELLAGAMBA, LORENZO;BERTIN, ANTONIO;BOSCHERINI, DAVIDE;BRUNI, ALESSIA;BRUNI, GRAZIANO;CAFORIO, DAVIDE;DE CASTRO, STEFANO;DI SIPIO, RICCARDO;FABBRI, LAURA;FRANCHINI, MATTEO;GIACOBBE, BENEDETTO;MASSA, IGNAZIO GIACOMO;MENGARELLI, ALBERTO;MONZANI, SIMONE;PICCININI, MAURIZIO;RINALDI, LORENZO;ROMANO, MARINO;SBARRA, CARLA;SBRIZZI, ANTONIO;SEMPRINI CESARI, NICOLA;SPIGHI, ROBERTO;VALENTINETTI, SARA;VILLA, MAURO;I. Vivarelli;ZOCCOLI, ANTONIO;
2013

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 the t ̄ t signal when m t 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 ) = 1, a fourth-generation t quark with mass lower than 656 GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass ∼ 126 GeV at the LHC, upper limits are derived in the two-dimensional plane of BR ( t → Wb ) versus BR ( t → Ht ) ,where H is the Standard Model Higgs boson, for vector-like quarks of various masses
2013
G. Aad, T. Abajyan, B. Abbott, J. Abdallah, S. Abdel Khalek, A.A. Abdelalim, et al. (2013). Search for pair production of heavy top-like quarks decaying to a high- W boson and a b quark in the lepton plus jets final state at with the ATLAS detector. PHYSICS LETTERS. SECTION B, 718, 1284-1302 [10.1016/j.physletb.2012.11.071].
G. Aad;T. Abajyan;B. Abbott;J. Abdallah;S. Abdel Khalek;A.A. Abdelalim;O. Abdinov;R. Aben;B. Abi;M. Abolins;O.S. AbouZeid;H. Abramowicz;H. Abreu;B.S. ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/142499
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