Evidence for the associated production of a single top quark and a photon in proton-proton collisions at $\sqrt{s}=$ 13 TeV

Abstract

The first evidence of events consistent with the production of a single top quark in association with a photon is reported. The analysis is based on proton-proton collisions at $\sqrt{s}=$ 13 TeV and recorded by the CMS experiment in 2016, corresponding to an integrated luminosity of 35.9 fb${}^{-1}$. Events are selected by requiring the presence of a muon ($\mu$), a photon ($\gamma$), an imbalance in transverse momentum from an undetected neutrino ($\nu$), and at least two jets (j) of which exactly one is identified as associated to the hadronization of a b quark. A multivariate discriminant based on topological and kinematic event properties is employed to separate signal from background processes. An excess above the background-only hypothesis is observed, with a significance of 4.4 standard deviations. A fiducial cross section is measured for isolated photons with transverse momentum greater than 25 GeV in the central region of the detector. The measured product of the cross section and branching fraction is $\sigma$(pp $\to$ t$\gamma$j)$\mathcal{B}$(t $\to$ $\mu \nu$b) = 115 $\pm$ 17 (stat) $\pm$ 30 (syst) fb, which is consistent with the standard model prediction.

arXiv commentReplaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-17-016 (CMS Public Pages)

References in corpus (42)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and Manual
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• The anti-k_t jet clustering algorithm
• A Brief Introduction to PYTHIA 8.1
• FastJet user manual
• A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX
• A New Method for Combining NLO QCD with Shower Monte Carlo Algorithms
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• Parton distributions for the LHC Run II
• Herwig++ Physics and Manual
• Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions
• Particle-flow reconstruction and global event description with the CMS detector
• Pileup subtraction using jet areas
• The CMS trigger system
• TMVA - Toolkit for Multivariate Data Analysis
• Description and performance of track and primary-vertex reconstruction with the CMS tracker
• Merging meets matching in MC@NLO
• Event generator tunes obtained from underlying event and multiparton scattering measurements
• Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV
• Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV
• Performance of electron reconstruction and selection with the CMS detector in proton-proton collisions at sqrt(s) = 8 TeV
• Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at sqrt(s) = 8 TeV
• Measurement of the Inelastic Proton-Proton Cross Section at $\sqrt{s}=13$ TeV with the ATLAS Detector at the LHC
• Top-pair production and decay at NLO matched with parton showers
• Measurement of the t-channel single top quark production cross section in pp collisions at sqrt(s) = 7 TeV
• Measurement of inclusive W and Z boson production cross sections in pp collisions at sqrt(s) = 8 TeV
• Measurement of the W+ W- cross section in pp collisions at sqrt(s) = 8 TeV and limits on anomalous gauge couplings
• Studies of Boosted Decision Trees for MiniBooNE Particle Identification
• Measurement of the W gamma and Z gamma inclusive cross sections in pp collisions at sqrt(s) = 7 TeV and limits on anomalous triple gauge boson couplings
• Cross section measurement of t-channel single top quark production in pp collisions at sqrt(s) = 13 TeV
• Measurement of W-gamma and Z-gamma production in pp collisions at sqrt(s) = 7 TeV
• Measurement of the cross section for electroweak production of Z gamma in association with two jets and constraints on anomalous quartic gauge couplings in proton-proton collisions at sqrt(s) = 8 TeV
• The SysCalc code: A tool to derive theoretical systematic uncertainties
• Evidence for t\bar{t}γProduction and Measurement of σ_t\bar{t}γ/ σ_t\bar{t}
• Measurement of electroweak-induced production of W gamma with two jets in pp collisions at sqrt(s) = 8 TeV and constraints on anomalous quartic gauge couplings
• Measurement of the semileptonic tt-bar gamma production cross section in pp collisions at sqrt(s) = 8 TeV
• Measuring anomalous WW$\gamma$ and t$\bar{\text{t}}\gamma$ couplings using top+$\gamma$ production at the LHC
• Measurement of the $t\bar{t}\gamma$ production cross section in proton-proton collisions at $\sqrt{s}=8$ TeV with the ATLAS detector
• Probing top quark electromagnetic dipole moments in single-top-plus-photon production
• Search for high-mass Z gamma resonances in proton-proton collisions at sqrt(s) = 8 and 13 TeV using jet substructure techniques

Cited by in corpus (11)

• Top-quark electroweak interactions at high energy
• The top quark electro-weak couplings after LHC Run 2
• Automated EW corrections with isolated photons: $t\bar{t}\gamma$, $t\bar{t}\gamma \gamma$ and $t\gamma j$ as case studies
• Search for flavor-changing neutral current interactions of the top quark and Higgs boson in final states with two photons in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Measurement of the top quark Yukawa coupling from $\mathrm{t}\bar{\mathrm{t}}$ kinematic distributions in the lepton+jets final state in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector
• Probing the nonstandard top-gluon couplings through $t\bar{t}\gamma \gamma$ production at the LHC
• Study of constraint and impact of a nuisance parameter in maximum likelihood method
• Photon radiation effects in kinematic reconstruction of top quarks
• Photon production in top quark events at ATLAS and CMS
• Searches for new interactions within the SMEFT framework at present and future colliders