Evidence for the associated production of a W boson and a top quark in ATLAS at √s = 7 TeV
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Aad-2012-Evidence for the ass.pdf
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1.06 MB
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Author(s)
Taylor, Frank E.
Date Issued
August 2012
Journal
Physics Letters B
Publisher
Elsevier
Citation
Aad, G., B. Abbott, J. Abdallah, S. Abdel Khalek, A.A. Abdelalim, O. Abdinov, B. Abi, et al. “Evidence for the Associated Production of a W Boson and a Top Quark in ATLAS At √s = 7 TeV” Physics Letters B 716, no. 1 (September 2012): 142–159. © 2012 CERN
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Final published version
Abstract
This Letter presents evidence for the associated production of a W boson and a top quark using 2.05 fb[superscript −1] of pp collision data at √s = 7 TeV accumulated with the ATLAS detector at the LHC. The analysis is based on the selection of the dileptonic final states with events featuring two isolated leptons, electron or muon, with significant transverse missing momentum and at least one jet. An approach based on boosted decision trees has been developed to improve the discrimination of single top-quark Wt events from background. A template fit to the final classifier distributions is performed to determine the cross-section. The result is incompatible with the background-only hypothesis at the 3.3σ level, the expected sensitivity assuming the Standard Model production rate being 3.4σ. The corresponding cross-section is determined and found to be σ[subscript Wt]=16.8±2.9 (stat)±4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element |V[subscript tb]| = 1.03[[subscript −0.19][superscript +0.16]] is derived assuming that the Wt production through |V[subscript ts]| and |V[subscript td]| is small.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1016/j.physletb.2012.08.011
