Search for associated production of a Z boson with a single top quark and for tZ flavour-changing interactions in pp collisions at sqrt(s) = 8 TeV

Abstract

A search for the production of a single top quark in association with a Z boson is presented, both to identify the expected standard model process and to search for flavour-changing neutral current interactions. The data sample corresponds to an integrated luminosity of 19.7 inverse femtobarns recorded by the CMS experiment at the LHC in proton-proton collisions at sqrt(s) = 8 TeV. Final states with three leptons (electrons or muons) and at least one jet are investigated. An events yield compatible with tZq standard model production is observed, and the corresponding cross section is measured to be sigma( p p -> t Z q -> l nu b l+ l- q ) = 10 +8/-7 fb with a significance of 2.4 standard deviations. No presence of flavour-changing neutral current production of tZq is observed. Exclusion limits at 95% confidence level on the branching fractions of a top quark decaying to a Z boson and an up or a charm quark are found to be B( t -> Z u ) < 0.022% and B( t -> Z c ) < 0.049%.

Replaced with the published version. Added the journal reference and DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-12-039

References in corpus (22)

• PYTHIA 6.4 Physics and Manual
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• An Introduction to PYTHIA 8.2
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• Vector boson pair production at the LHC
• The CMS trigger system
• Single-top Wt-channel production matched with parton showers using the POWHEG method
• Two-loop soft anomalous dimensions for single top quark associated production with a W- or H-
• Event generator tunes obtained from underlying event and multiparton scattering measurements
• Electroweak gauge boson production at hadron colliders through O(alpha_s^2)
• Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
• Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV
• Performance of electron reconstruction and selection with the CMS detector in proton-proton collisions at sqrt(s) = 8 TeV
• Measurement of the single-top-quark t-channel cross section in pp collisions at sqrt(s) = 7 TeV
• t tbar W and t tbar Z Hadroproduction at NLO accuracy in QCD with Parton Shower and Hadronization effects
• The RooStats Project
• A global approach to top-quark flavor-changing interactions
• Evidence for single top-quark production in the $s$-channel in proton-proton collisions at $\sqrt{s}=$8 TeV with the ATLAS detector using the Matrix Element Method
• Search for flavor changing neutral currents via quark-gluon couplings in single top quark production using 2.3 fb^-1 of ppbar collisions
• Measurement of top quark-antiquark pair production in association with a W or Z boson in pp collisions at sqrt(s) = 8 TeV
• Search for anomalous single top quark production in association with a photon in pp collisions at sqrt(s) = 8 TeV
• CT10 parton distributions and other developments in the global QCD analysis

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• Higgs Quark Flavor Violation: Simplified Models and Status of General Two-Higgs-Doublet Model
• Loop induced top quark FCNC through top quark and dark matter interactions
• Study of interference effects in the search for flavour-changing neutral current interactions involving the top quark and a photon or a $Z$ boson at the LHC
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• Probing FCNC couplings in single top quark production associated with a neutral gauge boson at future lepton colliders
• Soft-gluon corrections for single top quark production in association with electroweak bosons
• SM and BSM physics in single top quark at the LHC
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• Correlations in flavor-changing tqZ couplings constrained via experimental data
• Total and differential cross sections for Higgs and top-quark production
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• Single top-quark production via $tW$, $tZq$, and $s$-channel with ATLAS and CMS
• TOP2017: Experimental Summary