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

Abstract

This Letter presents evidence for single top-quark production in the $s$-channel using proton-proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS detector at the CERN Large Hadron Collider. The analysis is performed on events containing one isolated electron or muon, large missing transverse momentum and exactly two $b$-tagged jets in the final state. The analysed data set corresponds to an integrated luminosity of 20.3 fb${}^{-1}$. The signal is extracted using a maximum-likelihood fit of a discriminant which is based on the matrix element method and optimized in order to separate single-top-quark $s$-channel events from the main background contributions, which are top-quark pair production and $W$ boson production in association with heavy-flavour jets. The measurement leads to an observed signal significance of 3.2 standard deviations and a measured cross-section of ${\sigma }_s=4.8\pm 0.8$(stat.)${}_{-1.3}^{+1.6}$(syst.) pb, which is consistent with the Standard Model expectation. The expected significance for the analysis is 3.9 standard deviations.

16 pages plus author list + cover page (34 pages total), 4 figures, 2 tables, submitted to PLB. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2015-01/

References in corpus (23)

• 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
• Parton distributions for the LHC
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• New parton distributions for collider physics
• Event generation with SHERPA 1.1
• Vector boson pair production at the LHC
• Two-loop soft anomalous dimensions for single top quark associated production with a W- or H-
• MCFM for the Tevatron and the LHC
• Next-to-next-to-leading-order collinear and soft gluon corrections for t-channel single top quark production
• NNLL resummation for s-channel single top quark production
• The PDF4LHC Working Group Interim Recommendations
• Jet energy measurement and its systematic uncertainty in proton-proton collisions at $\sqrt{s}=7$ TeV with the ATLAS detector
• 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
• Search for the $b\bar{b}$ decay of the Standard Model Higgs boson in associated $(W/Z)H$ production with the ATLAS detector
• Measurement of the single-top-quark t-channel cross section in pp collisions at sqrt(s) = 7 TeV
• Measurement of the charge asymmetry in top quark pair production in pp collisions at sqrt(s) = 7 TeV using the ATLAS detector
• Evidence for production of single top quarks and first direct measurement of |Vtb|
• 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
• Muon reconstruction efficiency and momentum resolution of the ATLAS experiment in proton-proton collisions at $\sqrt{s}$=7 TeV in 2010
• Search for s-channel single top-quark production in proton-proton collisions at $\sqrt{s}$=8 TeV with the ATLAS detector

Cited by in corpus (41)

• The Standard Model as an Effective Field Theory
• O new physics, where art thou? A global search in the top sector
• Single-top associated production with a $Z$ or $H$ boson at the LHC: the SMEFT interpretation
• Off-shell single-top production at NLO matched to parton showers
• Search for pair production of heavy vector-like quarks decaying into hadronic final states in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• 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
• Two Invertible Networks for the Matrix Element Method
• Measurement of the associated production of a single top quark and a Z boson in pp collisions at $\sqrt{s}=$ 13 TeV
• Single top-quark production at the Tevatron and the LHC
• Soft anomalous dimensions for single-top production at three loops
• Search for s channel single top quark production in pp collisions at sqrt(s) = 7 and 8 TeV
• Top-Quark Physics: Status and Prospects
• Machine Learning in High Energy Physics Community White Paper
• New limits on anomalous contributions to the $Wtb$ vertex
• The Matrix Element Method at next-to-leading order QCD for hadronic collisions: Single top-quark production at the LHC as an example application
• Constraining the SMEFT with Bayesian reweighting
• s-channel Single Top Quark Production and Decay at NNLO in QCD
• Topological Reconstruction of Particle Physics Processes using Graph Neural Networks
• Probing anomalous $Wtb$ couplings at the LHC in single top quark production through $t$-channel
• Precision-Machine Learning for the Matrix Element Method
• Single top-quark production with SHERPA
• Soft-gluon corrections in top-quark production
• Matrix Element Method at NLO for (anti-)${\mathbf{k}}_{\mathbf{t}}$-jet algorithms
• Top-quark physics at the Large Hadron Collider
• Matrix Element Regression with Deep Neural Networks -- breaking the CPU barrier
• Global Constraints on Top Quark Anomalous Couplings
• MoMEMta, a modular toolkit for the Matrix Element Method at the LHC
• Observation of tW production in the single-lepton channel in pp collisions at $\sqrt{s}$ = 13 TeV
• Climbing to the Top of the ATLAS 13 TeV data
• Top Quark Anomalous Couplings at the High-Luminosity Phase of the LHC
• Staying on Top of SMEFT-Likelihood Analyses
• Next-to-leading order QCD corrections for single top-quark production in association with two jets
• SM and BSM physics in single top quark at the LHC
• Single-top and top-antitop cross sections
• 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
• Single-top production and rare top interactions
• Reduction of planar double-box diagram for single-top production via auxiliary mass flow
• A Novel Implementation of the Matrix Element Method at Next-to-Leading Order for the Measurement of the Higgs Self-Coupling ${\lambda }_{3H}$
• Searches for new interactions within the SMEFT framework at present and future colliders
• Measurement of the $t\bar{t}Z$ Production Cross Section in the Final State with Three Charged Leptons using 36.1 fb${}^{-1}$ of $pp$ Collisions at 13 TeV at the ATLAS Detector