Search for flavor-changing neutral currents in top quark decays $t\to Hc$ and $t\to Hu$ in multilepton final states in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

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 $\mathcal{B}(t\to Hu)<$ 0.19% at 95% confidence level are obtained (with expected limits of 0.15% in both cases).

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/

References in corpus (16)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• New parton distributions for collider physics
• Event generation with SHERPA 1.1
• Automatic spin-entangled decays of heavy resonances in Monte Carlo simulations
• The PDF4LHC Working Group Interim Recommendations
• Luminosity determination in pp collisions at $\sqrt{s}$ = 8 TeV using the ATLAS detector at the LHC
• Performance of missing transverse momentum reconstruction with the ATLAS detector using proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Collider Signals of Top Quark Flavor Violation from a Warped Extra Dimension
• Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector
• Composite Higgs-Mediated FCNC
• Search for anomalous Wtb couplings and flavour-changing neutral currents in t-channel single top quark production in pp collisions at sqrt(s) = 7 and 8 TeV
• Search for top quark decays $t\to qH$ with $H\to \gamma \gamma$ using the ATLAS detector
• The SysCalc code: A tool to derive theoretical systematic uncertainties
• Search for the flavor-changing neutral current interactions of the top quark and the Higgs boson which decays into a pair of b quarks at $\sqrt{s}=$ 13 TeV
• Search for top quark decays $t\to qH$, with $H\to \gamma \gamma$, in $\sqrt{s}=13$ TeV $pp$ collisions using the ATLAS detector
• Search for top quark decays via Higgs-boson-mediated flavor-changing neutral currents in pp collisions at sqrt(s) = 8 TeV

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