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

G. Aad; B. Abbott; Mogens Dam; Jørgen Beck Hansen; Peter Henrik Hansen; John Renner Hansen; Jørn Dines Hansen; Simon Johann Franz Heisterkamp; Morten Dam Jørgensen; Nele Maria Philomena Boelaert; Esben Bryndt Klinkby; Sascha Mehlhase; Björn Stefan Nilsson; Troels Christian Petersen; Stefania Xella; Ask Emil Løvschall-Jensen

doi:10.1016/j.physletb.2012.08.011

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

G. Aad, B. Abbott, Mogens Dam, Jørgen Beck Hansen, Peter Henrik Hansen, John Renner Hansen, Jørn Dines Hansen, Simon Johann Franz Heisterkamp, Morten Dam Jørgensen, Nele Maria Philomena Boelaert, Esben Bryndt Klinkby, Sascha Mehlhase, Björn Stefan Nilsson, Troels Christian Petersen, Stefania Xella, Ask Emil Løvschall-Jensen

Experimental Particle Physics

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
Journal	Physics Letters B
Volume	716
Issue number	1
Pages (from-to)	142-159
Number of pages	17
ISSN	0370-2693
DOIs	https://doi.org/10.1016/j.physletb.2012.08.011
Publication status	Published - 17 Sept 2012

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Aad, G., Abbott, B., Dam, M., Hansen, J. B., Hansen, P. H., Hansen, J. R., Hansen, J. D., Heisterkamp, S. J. F., Jørgensen, M. D., Boelaert, N. M. P., Klinkby, E. B., Mehlhase, S., Nilsson, B. S., Petersen, T. C., Xella, S., & Løvschall-Jensen, A. E. (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), 142-159. https://doi.org/10.1016/j.physletb.2012.08.011

Aad, G, Abbott, B, Dam, M , Hansen, JB , Hansen, PH , Hansen, JR , Hansen, JD, Heisterkamp, SJF, Jørgensen, MD, Boelaert, NMP, Klinkby, EB, Mehlhase, S, Nilsson, BS, Petersen, TC , Xella, S & Løvschall-Jensen, AE 2012, 'Evidence for the associated production of a W boson and a top quark in ATLAS at root s=7 TeV', Physics Letters B, vol. 716, no. 1, pp. 142-159. https://doi.org/10.1016/j.physletb.2012.08.011

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

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.",

author = "G. Aad and B. Abbott and Mogens Dam and Hansen, {J{\o}rgen Beck} and Hansen, {Peter Henrik} and Hansen, {John Renner} and Hansen, {J{\o}rn Dines} and Heisterkamp, {Simon Johann Franz} and J{\o}rgensen, {Morten Dam} and Boelaert, {Nele Maria Philomena} and Klinkby, {Esben Bryndt} and Sascha Mehlhase and Nilsson, {Bj{\"o}rn Stefan} and Petersen, {Troels Christian} and Stefania Xella and L{\o}vschall-Jensen, {Ask Emil}",

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

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

AU - Aad, G.

AU - Abbott, B.

AU - Dam, Mogens

AU - Hansen, Jørgen Beck

AU - Hansen, Peter Henrik

AU - Hansen, John Renner

AU - Hansen, Jørn Dines

AU - Heisterkamp, Simon Johann Franz

AU - Jørgensen, Morten Dam

AU - Boelaert, Nele Maria Philomena

AU - Klinkby, Esben Bryndt

AU - Mehlhase, Sascha

AU - Nilsson, Björn Stefan

AU - Petersen, Troels Christian

AU - Xella, Stefania

AU - Løvschall-Jensen, Ask Emil

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.

U2 - 10.1016/j.physletb.2012.08.011

DO - 10.1016/j.physletb.2012.08.011

M3 - Journal article

SN - 0370-2693

VL - 716

SP - 142

EP - 159

JO - Physics Letters B: Particle Physics, Nuclear Physics and Cosmology

JF - Physics Letters B: Particle Physics, Nuclear Physics and Cosmology

IS - 1

ER -

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

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