Probing the $Wtb$ vertex structure in $t$-channel single-top-quark production and decay in $pp$ collisions at $\sqrt{\mathrm{s}}=8$ TeV with the ATLAS detector

Abstract

To probe the $Wtb$ vertex structure, top-quark and $W$-boson polarisation observables are measured from $t$-channel single-top-quark events produced in proton--proton collisions at a centre-of-mass energy of 8 TeV. The dataset corresponds to an integrated luminosity of 20.2 fb${}^{-1}$, recorded with the ATLAS detector at the LHC. Selected events contain one isolated electron or muon, large missing transverse momentum and exactly two jets, with one of them identified as likely to contain a $b$-hadron. Stringent selection requirements are applied to discriminate $t$-channel single-top-quark events from background. The polarisation observables are extracted from asymmetries in angular distributions measured with respect to spin quantisation axes appropriately chosen for the top quark and the $W$ boson. The asymmetry measurements are performed at parton level by correcting the observed angular distributions for detector effects and hadronisation after subtracting the background contributions. The measured top-quark and $W$-boson polarisation values are in agreement with the Standard Model predictions. Limits on the imaginary part of the anomalous coupling $g_{\mathrm{R}}$ are also set from model-independent measurements.

48 pages in total, author list starting page 32, 10 figures, 5 tables. Submitted to JHEP. All figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2014-17/

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
• 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-
• Single-top hadroproduction in association with a W boson
• FEWZ 2.0: A code for hadronic Z production at next-to-next-to-leading order
• 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
• Luminosity determination in pp collisions at $\sqrt{s}$ = 8 TeV using the ATLAS detector at the LHC
• 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
• Next-to-leading-order predictions for t-channel single-top production at hadron colliders
• Single top quark production at LHC with anomalous Wtb couplings
• Measurements of the W production cross sections in association with jets with the ATLAS detector
• Performance of the ATLAS muon trigger in pp collisions at $\sqrt{s}=8$ TeV
• Single top quark production and decay in the t-channel at next-to-leading order at the LHC
• New directions for top quark polarization in the $t$-channel process

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• Inclusive and differential cross section measurements of single top quark production in association with a Z boson in proton-proton collisions at $\sqrt{s}$ = 13 TeV
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• SM and BSM physics in single top quark at the LHC
• Bread and butter physics: NLO electroweak corrections to polarized top quark decays
• HEP-Frame: an Efficient Tool for Big Data Applications at the LHC
• NLO and NNLO corrections to polarized top quark decays
• Measuring quark polarizations at ATLAS and CMS
• Top quark properties measurements at the LHC
• $O({\alpha }_s)$ perturbative and nonperturbative corrections to polarized semileptonic ${\Lambda }_b$ decay distributions