Search for flavor-changing neutral currents in top quark decays <i>t</i> → <i>Hc</i> and <i>t</i> → <i>Hu</i> in multilepton final states in proton-proton collisions at √<i>s</i>=13 TeV with the ATLAS detector



Aaboud, M, Aad, G, Abbott, B, Abdinov, O, Abeloos, B, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H
et al (show 2885 more authors) (2018) Search for flavor-changing neutral currents in top quark decays <i>t</i> → <i>Hc</i> and <i>t</i> → <i>Hu</i> in multilepton final states in proton-proton collisions at √<i>s</i>=13 TeV with the ATLAS detector. PHYSICAL REVIEW D, 98 (3). 032002-.

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Abstract

Flavor-changing neutral currents are not present in the Standard Model at tree level and are suppressed in loop processes by the unitarity of the Cabibbo-Kobayashi-Maskawa matrix; the corresponding rates for top quark decay processes are experimentally unobservable. Extensions of the Standard Model can generate new flavor-changing neutral current processes, leading to signals which, if observed, would be unambiguous evidence of new interactions. A dataset corresponding to an integrated luminosity of 36.1 fb$^{-1}$ of $pp$ collisions at a center-of-mass energy of $\sqrt{s}=$ 13 TeV recorded with the ATLAS detector at the Large Hadron Collider is used to search for top quarks decaying to up or charm quarks with the emission of a Higgs boson, with subsequent Higgs boson decay to final states with at least one electron or muon. No signal is observed and limits on the branching fractions $\mathcal{B}(t \to Hc) <$ 0.16% and $\mathcal{B}(t \to H u) <$ 0.19% at 95% confidence level are obtained (with expected limits of 0.15% in both cases).

Item Type: Article
Additional Information: 36 pages, author list starting at page 20, 3 figures, 4 tables, published in Phys. Rev. D. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2017-15/
Uncontrolled Keywords: hep-ex, hep-ex
Depositing User: Symplectic Admin
Date Deposited: 30 Aug 2018 15:16
Last Modified: 10 Oct 2023 13:20
DOI: 10.1103/PhysRevD.98.032002
Open Access URL: https://journals.aps.org/prd/abstract/10.1103/Phys...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3025733