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

ATLAS Collaboration

doi:10.1016/j.physletb.2012.08.011

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

ATLAS Collaboration

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Research output: Contribution to journal › Article › peer-review

107 Scopus citations

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 σ_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_tb|=1.03_−0.19 ^+0.16 is derived assuming that the Wt production through |V_ts| and |V_td| is small.

Original language	English
Pages (from-to)	142-159
Number of pages	18
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	716
Issue number	1
DOIs	https://doi.org/10.1016/j.physletb.2012.08.011
State	Published - 17 Sep 2012
Externally published	Yes

Keywords

ATLAS
Single top-quark
Top quark
W+t

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10.1016/j.physletb.2012.08.011

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@article{3a7b659a5e0d43728946667be9d89fc5,

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

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.",

keywords = "ATLAS, Single top-quark, Top quark, W+t",

author = "G. Aad and B. Abbott and J. Abdallah and \{Abdel Khalek\}, S. and S. Kabana and \{ATLAS Collaboration\}",

note = "Publisher Copyright: {\textcopyright} 2012 CERN",

year = "2012",

month = sep,

day = "17",

doi = "10.1016/j.physletb.2012.08.011",

language = "English",

volume = "716",

pages = "142--159",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

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}

TY - JOUR

T1 - Evidence for the associated production of a W boson and a top quark in ATLAS at √s=7TeV

AU - Aad, G.

AU - Abbott, B.

AU - Abdallah, J.

AU - Abdel Khalek, S.

AU - Kabana, S.

AU - ATLAS Collaboration

PY - 2012/9/17

Y1 - 2012/9/17

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

UR - https://www.scopus.com/pages/publications/85042037870

U2 - 10.1016/j.physletb.2012.08.011

DO - 10.1016/j.physletb.2012.08.011

M3 - Article

AN - SCOPUS:85042037870

SN - 0370-2693

VL - 716

SP - 142

EP - 159

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

IS - 1

ER -

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

Abstract

Keywords

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