Evidence for the associated production of a W boson and a top quark in ATLAS at root s=7 TeV

Barton, Adam and Borissov, Guennadi and Bouhova-Thacker, Eva and Chilingarov, Alexandre and Davidson, Ruth and de Mora, Lee and Dearnaley, William and Fox, Harald and Henderson, Robert and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin and Love, Peter and Smizanska, Maria and Walder, James (2012) Evidence for the associated production of a W boson and a top quark in ATLAS at root s=7 TeV. Physics Letters B, 716 (1). pp. 142-159. ISSN 0370-2693

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This Letter presents evidence for the associated production of a W boson and a top quark using 2.05 fb(-1) of pp collision data at root 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 3.3 sigma level, the expected sensitivity assuming the Standard Model production rate being 3.4 sigma. The corresponding cross-section is determined and found to be sigma(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 vertical bar V-tb vertical bar = 1.03(-0.19)(+0.16) is derived assuming that the Wt production through vertical bar V-ts vertical bar and vertical bar V-td vertical bar is small.

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Journal Article
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Physics Letters B
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This article is published Open Access at sciencedirect.com. It is distributed under the terms of the Creative Commons Attribution License 3.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
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17 Dec 2013 00:03
Last Modified:
10 Jul 2020 03:12