Measurement of the production cross-section of a single top quark in association with a $W$ boson at 8 TeV with the ATLAS experiment

Abstract

The cross-section for the production of a single top quark in association with a $W$ boson in proton--proton collisions at $\sqrt{s}=8$ TeV is measured. The dataset corresponds to an integrated luminosity of 20.3 fb${}^{-1}$, collected by the ATLAS detector in 2012 at the Large Hadron Collider at CERN. Events containing two leptons and one central $b$-jet are selected. The $Wt$ signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of $Wt$ events is observed with a significance of $7.7\sigma$. The cross-section is extracted in a profile likelihood fit to the classifier output distributions. The $Wt$ cross-section, inclusive of decay modes, is measured to be $23.0\pm 1.3$(stat.)${}_{-3.5}^{+3.2}$(syst.)$\pm 1.1$(lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element $|V_{tb}|$ of $1.01\pm 0.10$ and a lower limit of 0.80 at the 95\% confidence level. The cross-section for the production of a top quark and a $W$ boson is also measured in a fiducial acceptance requiring two leptons with $p_{\text{T}}>25$ GeV and $|\eta |<2.5$, one jet with $p_{\text{T}}>20$ GeV and $|\eta |<2.5$, and $E_{\text{T}}^{\text{miss}}>20$ GeV, including both $Wt$ and top-quark pair events as signal. The measured value of the fiducial cross-section is $0.85\pm 0.01$(stat.)${}_{-0.07}^{+0.06}$(syst.)$\pm 0.03$(lumi.) pb.

34 pages plus author list + cover page (51 pages total), 11 figures, 6 tables, submitted to JHEP, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2012-20/

References in corpus (27)

• PYTHIA 6.4 Physics and Manual
• Parton distributions for the LHC
• New parton distributions for collider physics
• Implications of CTEQ global analysis for collider observables
• Performance of the ATLAS Trigger System in 2015
• Two-loop soft anomalous dimensions for single top quark associated production with a W- or H-
• -- HATHOR -- HAdronic Top and Heavy quarks crOss section calculatoR
• Single-top hadroproduction in association with a W boson
• Electroweak gauge boson production at hadron colliders through O(alpha_s^2)
• The PDF4LHC Working Group Interim Recommendations
• HATHOR for single top-quark production: Updated predictions and uncertainty estimates for single top-quark production in hadronic collisions
• Jet energy measurement and its systematic uncertainty in proton-proton collisions at $\sqrt{s}=7$ TeV with the ATLAS detector
• Electron and photon energy calibration with the ATLAS detector using LHC Run 1 data
• Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton-proton collision data
• Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton-proton collision data
• Electron efficiency measurements with the ATLAS detector using 2012 LHC proton-proton collision data
• Precise Predictions for W + 4 Jet Production at the Large Hadron Collider
• A practical Seedless Infrared-Safe Cone jet algorithm
• Measurement of the single-top-quark t-channel cross section in pp collisions at sqrt(s) = 7 TeV
• Minimal Kinematic Constraints and MT2
• Efficient Identification of Boosted Semileptonic Top Quarks at the LHC
• The RooStats Project
• Evidence for associated production of a single top quark and W boson in pp collisions at sqrt(s) = 7 TeV
• Search for New Physics via Single Top Production at the LHC
• Tevatron Combination of Single-Top-Quark Cross Sections and Determination of the Magnitude of the Cabibbo-Kobayashi-Maskawa Matrix Element ${\mathbf{V}}_{\mathbf{tb}}$
• Search for s-channel single top-quark production in proton-proton collisions at $\sqrt{s}$=8 TeV with the ATLAS detector
• Determining $V_{tb}$ at Electron-Positron Colliders

Cited by in corpus (42)

• The Standard Model as an Effective Field Theory
• O new physics, where art thou? A global search in the top sector
• Constraining the top-Higgs sector of the Standard Model Effective Field Theory
• An NLO+PS generator for $t\bar{t}$ and $Wt$ production and decay including non-resonant and interference effects
• Right-handed charged currents in the era of the Large Hadron Collider
• Search for heavy resonances decaying into $WW$ in the $e\nu \mu \nu$ final state in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Measurement of total and differential $W^{+}{W}^{-}$ production cross sections in proton-proton collisions at $\sqrt{s}=$ 8 TeV with the ATLAS detector and limits on anomalous triple-gauge-boson couplings
• Measurement of the cross-section for producing a $W$ boson in association with a single top quark in $pp$ collisions at $\sqrt{s}=13$ TeV with ATLAS
• Measurement of the production cross-section of a single top quark in association with a $Z$ boson in proton--proton collisions at 13 TeV with the ATLAS detector
• Software and computing for Run 3 of the ATLAS experiment at the LHC
• Measurement of the production cross section for single top quarks in association with W bosons in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• 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
• Soft-gluon corrections for $tW$ production at N${}^3$LO
• Measurement of the associated production of a single top quark and a Z boson in pp collisions at $\sqrt{s}=$ 13 TeV
• Study of $WW\gamma$ and $WZ\gamma$ production in $pp$ collisions at $\sqrt{s}=8$ TeV and search for anomalous quartic gauge couplings with the ATLAS experiment
• Single top-quark production at the Tevatron and the LHC
• Top-Quark Physics: Status and Prospects
• Measurement of differential cross-sections of a single top quark produced in association with a $W$ boson at $\sqrt{s}=13$ TeV with ATLAS
• New limits on anomalous contributions to the $Wtb$ vertex
• Combined SMEFT interpretation of Higgs, diboson, and top quark data from the LHC
• Top physics at the LHC
• Probing anomalous $Wtb$ couplings at the LHC in single top quark production through $t$-channel
• Single top-quark production with SHERPA
• Top-quark physics at the Large Hadron Collider
• Measurement of single top-quark production in association with a $W$ boson in the single-lepton channel at $\sqrt{s}=8$ TeV with the ATLAS detector
• Analytic two-loop master integrals for $tW$ production at hadron colliders: I
• Momentum-space threshold resummation in $tW$ production at the LHC
• Measuring $|V_{td}|$ at LHC
• Observation of tW production in the single-lepton channel in pp collisions at $\sqrt{s}$ = 13 TeV
• Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector
• One-loop squared amplitudes for hadronic $tW$ production at next-to-next-to-leading order in QCD
• Investigating the Quantum Properties of Jets and the Search for a Supersymmetric Top Quark Partner with the ATLAS Detector
• Climbing to the Top of the ATLAS 13 TeV data
• Measurement of single top-quark production in association with a $W$ boson in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Staying on Top of SMEFT-Likelihood Analyses
• Single-top quark physics at the LHC: from precision measurements to rare processes and top quark properties
• A Global Analysis of the Standard Model Effective Field Theory in the Production and Decay Channels of a Single Top Quark
• Single top-quark production via $tW$, $tZq$, and $s$-channel with ATLAS and CMS
• Searches for new interactions within the SMEFT framework at present and future colliders
• Measurement of tW the production cross-section at 13 TeV with CMS
• Approximate N${}^2$LO and N${}^3$LO QCD Predictions for $tW$ Production
• Reduction of planar double-box diagram for single-top production via auxiliary mass flow