Search for pair production of heavy top-like quarks decaying to a high-p(T) W boson and a b quark in the lepton plus jets final state at root s=7 TeV with the ATLAS detector
2013 (English)In: Physics Letters B, ISSN 0370-2693, Vol. 718, no 4-5, 1284-1302 p.Article in journal (Refereed) Published
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=7TeV 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't̄' signal when mt'≳400GeV. 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 656GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass ~126GeV 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.
Place, publisher, year, edition, pages
2013. Vol. 718, no 4-5, 1284-1302 p.
IdentifiersURN: urn:nbn:se:uu:diva-194967DOI: 10.1016/j.physletb.2012.11.071ISI: 000314554300014OAI: oai:DiVA.org:uu-194967DiVA: diva2:606734
ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1016/j.physletb.2012.11.0712013-02-202013-02-202013-05-02Bibliographically approved