Search for Flavour-Changing Neutral Current Top Quark Decays t → Hq In pp Collisions at √s̅ = 8 TeV with the ATLAS Detector

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dc.contributor.VIAF250674117 (Izen, JM)en_US
dc.contributor.VIAF250674117 (Izen, JM)
dc.contributor.authorAad, G.en_US
dc.contributor.authorAbbott, B.en_US
dc.contributor.authorAbdallah, J.en_US
dc.contributor.authorAbdinov, O.en_US
dc.contributor.authorAben, R.en_US
dc.contributor.authorAbolins, M.en_US
dc.contributor.authorAbouZeid, O. S.en_US
dc.contributor.authorIzen, Joseph M.en_US
dc.contributor.authorLeyton, Michaelen_US
dc.contributor.authorMeirose, Bernharden_US
dc.contributor.authorNamasivayam, Harisankaren_US
dc.contributor.authorReeves, Kendallen_US
dc.contributor.authorATLAS Collaborationen_US
dc.contributor.utdAuthorIzen, Joseph M.en_US
dc.contributor.utdAuthorLeyton, Michaelen_US
dc.contributor.utdAuthorMeirose, Bernharden_US
dc.contributor.utdAuthorNamasivayam, Harisankaren_US
dc.contributor.utdAuthorReeves, Kendallen_US
dc.date.accessioned2016-07-06T18:59:57Z
dc.date.available2016-07-06T18:59:57Z
dc.date.created2015-12-10en_US
dc.date.issued2015-12-10en_US
dc.description.abstractA search for flavour-changing neutral current decays of a top quark to an up-type quark (q = u; c) and the Standard Model Higgs boson, where the Higgs boson decays to b (b) over bar, is presented. The analysis searches for top quark pair events in which one top quark decays to W b, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at root s = 8TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb(-1). Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by t (t) over bar -> WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t -> Hc and t -> Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H -> gamma gamma and H -> WW*, tau tau decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t -> Hc and t -> Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the vertical bar lambda(tcH)vertical bar and vertical bar lambda(tuH)vertical bar couplings are 0.13 (0.10) and 0.13 (0.10) respectively. These are the most restrictive direct bounds on t q H interactions measured so far.en_US
dc.identifier.bibliographicCitationAad, G., B. Abbott, J. Abdallah, O. Abdinov, et al. 2015. "Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s̅ = 8 TeV with the ATLAS detector." Journal of High Energy Physics 2015(5), doi:10.1007/JHEP12(2015)061.en_US
dc.identifier.issn1029-8479en_US
dc.identifier.issue12en_US
dc.identifier.urihttp://hdl.handle.net/10735.1/4890
dc.identifier.volume2015en_US
dc.language.isoenen_US
dc.publisherSpringeren_US
dc.relation.urihttp://dx.doi.org/10.1007/JHEP12(2015)061
dc.rightsCC BY 4.0 (Attribution)en_US
dc.rights©2015 CERN, for the ATLAS Collaborationen_US
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en_US
dc.sourceJournal of High Energy Physics
dc.subjectHadron-hadron scatteringen_US
dc.subjectTop Quarksen_US
dc.subjectHiggs bosonsen_US
dc.subjectStandard Modelen_US
dc.subjectPartonsen_US
dc.subjectHadronsen_US
dc.subjectHadron-hadron scatteringen_US
dc.subjectCollisionsen_US
dc.titleSearch for Flavour-Changing Neutral Current Top Quark Decays t → Hq In pp Collisions at √s̅ = 8 TeV with the ATLAS Detectoren_US
dc.type.genreArticleen_US

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Izen, Joseph M.