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dc.contributor.authorAaboud, M.
dc.contributor.authorAad, G.
dc.contributor.authorAbbott, B.
dc.contributor.authorAbbott, D. C.
dc.contributor.authorAbdinov, O.
dc.contributor.authorAbeloos, B.
dc.contributor.authorAbhayasinghe, D. K.
dc.contributor.authorIzen, Joseph M.
dc.contributor.authorMeirose, Bernhard
dc.contributor.authorReeves, Kendall
dc.contributor.authorATLAS collaboration
dc.description.abstractA search for flavour-changing neutral current decays of a top quark into an up-type quark (q = u, c) and the Standard Model Higgs boson, t → Hq, is presented. The search is based on a dataset of pp collisions at s = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 36.1 fb⁻¹. Two complementary analyses are performed to search for top-quark pair events in which one top quark decays into Wb and the other top quark decays into Hq, and target the H→ bb̅ and H → τ⁺τ⁻ decay modes, respectively. The high multiplicity of b-quark jets, or the presence of hadronically decaying τ-leptons, is exploited in the two analyses respectively. Multivariate techniques are used to separate the signal from the background, which is dominated by top-quark pair production. No significant excess of events above the background expectation is found, and 95% CL upper limits on the t → Hq branching ratios are derived. The combination of these searches with ATLAS searches in diphoton and multilepton final states yields observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 1.1 × 10⁻³ (8.3 × 10⁻⁴) and 1.2 × 10⁻³ (8.3 × 10⁻⁴), respectively. The corresponding combined observed (expected) upper limits on the |λ_{tcH}| and |λ_{tuH}| couplings are 0.064 (0.055) and 0.066 (0.055), respectively. ©2019, The Author(s).
dc.publisherSpringer Verlag
dc.rightsCC BY 4.0 (Attribution)
dc.rights©2019 CERN for the benefit of the ATLAS Collaboration
dc.subjectParticles (Nuclear physics)--Flavor
dc.subjectLarge Hadron Collider (France and Switzerland)
dc.subjectProton-proton interactions
dc.subjectStandard model (Nuclear physics)
dc.subjectHiggs bosons
dc.titleSearch for Top-Quark Decays t → Hq with 36 fb⁻¹ of pp Collision Data at √s = 13 TeV with the ATLAS Detector
dc.description.departmentSchool of Natural Sciences and Mathematics
dc.identifier.bibliographicCitationAaboud, M., G. Aad, B. Abbott, D. C. Abbott, et al. 2019. "Search for top-quark decays t → Hq with 36 fb⁻¹ of pp collision data at √s = 13 TeV with the ATLAS detector." Journal of High Energy Physics 2019(5): art. 123, doi: 10.1007/JHEP05(2019)123
dc.source.journalJournal of High Energy Physics
dc.contributor.utdAuthorIzen, Joseph M.
dc.contributor.utdAuthorMeirose, Bernhard
dc.contributor.utdAuthorReeves, Kendall
dc.contributor.VIAF250674117 (Izen, JM)

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