Search for top quark decays $t\to qH$, with $H\to \gamma \gamma$, in $\sqrt{s}=13$ TeV $pp$ collisions using the ATLAS detector

Abstract

This article presents a search for flavour-changing neutral currents in the decay of a top quark into an up-type ($q=c,u$) quark and a Higgs boson, where the Higgs boson decays into two photons. The proton--proton collision data set analysed amounts to 36.1 fb${}^{-1}$ at $\sqrt{s}=13$ TeV collected by the ATLAS experiment at the LHC. Top quark pair events are searched for, where one top quark decays into $qH$ and the other decays into $bW$. Both the hadronic and leptonic decay modes of the $W$ boson are used. No significant excess is observed and an upper limit is set on the $t\to cH$ branching ratio of $2.2\times 10^{-3}$ at the 95% confidence level, while the expected limit in the absence of signal is $1.6\times 10^{-3}$. The corresponding limit on the $tcH$ coupling is 0.090 at the 95% confidence level. The observed upper limit on the $t\to uH$ branching ratio is $2.4\times 10^{-3}$.

41 pages in total, author list starting page 25, 7 figures, 3 tables, submitted to JHEP. All figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2016-26/

References in corpus (20)

• Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
• Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC
• 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
• Implications of CTEQ global analysis for collider observables
• Combined Measurement of the Higgs Boson Mass in $pp$ Collisions at $\sqrt{s}=7$ and 8 TeV with the ATLAS and CMS Experiments
• Pileup subtraction using jet areas
• Luminosity determination in pp collisions at $\sqrt{s}$ = 8 TeV using the ATLAS detector at the LHC
• Measurement of the $Z/{\gamma }^{\ast }$ boson transverse momentum distribution in $pp$ collisions at $\sqrt{s}$ = 7 TeV with the ATLAS detector
• Measurement of Higgs boson production in the diphoton decay channel in $pp$ collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector
• Electron and photon energy calibration with the ATLAS detector using LHC Run 1 data
• Collider Signals of Top Quark Flavor Violation from a Warped Extra Dimension
• SUSY-induced FCNC top-quark processes at the Large Hadron Collider
• tWH associated production at the LHC
• Composite Higgs-Mediated FCNC
• Automatic computations at next-to-leading order in QCD for top-quark flavor-changing neutral processes
• Search for top quark decays $t\to qH$ with $H\to \gamma \gamma$ using the ATLAS detector
• Scalar FCNC and rare top decays in a two Higgs doublet model "for the top"
• Search for top quark decays via Higgs-boson-mediated flavor-changing neutral currents in pp collisions at sqrt(s) = 8 TeV

Cited by in corpus (2)

• Charming Top Decays with Flavor Changing Neutral Higgs Boson and WW at Hadron Colliders
• TOP2017: Experimental Summary