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

ATLAS Collaboration

Research output: Contribution to journalArticle

78 Citations (Scopus)

Abstract

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 s=7TeV 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 σWt=16.8±2.9 (stat)±4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element |Vtb|=1.03−0.19 +0.16 is derived assuming that the Wt production through |Vts| and |Vtd| is small.

Original languageEnglish
Pages (from-to)142-159
Number of pages18
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume716
Issue number1
DOIs
Publication statusPublished - Sep 17 2012
Externally publishedYes

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bosons
quarks
cross sections
classifiers
discrimination
leptons
muons
templates
momentum
collisions
sensitivity
detectors
matrices
electrons

Keywords

  • ATLAS
  • Single top-quark
  • Top quark
  • W+t

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Evidence for the associated production of a W boson and a top quark in ATLAS at √s=7TeV. / ATLAS Collaboration.

In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol. 716, No. 1, 17.09.2012, p. 142-159.

Research output: Contribution to journalArticle

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abstract = "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 s=7TeV 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 σWt=16.8±2.9 (stat)±4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element |Vtb|=1.03−0.19 +0.16 is derived assuming that the Wt production through |Vts| and |Vtd| is small.",
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AU - Adye, T.

AU - Aefsky, S.

AU - Aguilar-Saavedra, J. A.

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AU - Ahles, F.

AU - Ahmad, A.

AU - Ahsan, M.

AU - Aielli, G.

AU - Akdogan, T.

AU - Åkesson, T. P.A.

AU - Akimoto, G.

AU - Akimov, A. V.

AU - Akiyama, A.

AU - Alam, M. S.

AU - Alam, M. A.

AU - Albert, J.

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AU - Alessandria, F.

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AU - Alexander, G.

AU - Alexandre, G.

AU - Alexopoulos, T.

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N2 - 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 s=7TeV 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 σWt=16.8±2.9 (stat)±4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element |Vtb|=1.03−0.19 +0.16 is derived assuming that the Wt production through |Vts| and |Vtd| is small.

AB - 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 s=7TeV 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 σWt=16.8±2.9 (stat)±4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element |Vtb|=1.03−0.19 +0.16 is derived assuming that the Wt production through |Vts| and |Vtd| is small.

KW - ATLAS

KW - Single top-quark

KW - Top quark

KW - W+t

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