Measurement of the production cross-section of a single top quark in association with a W boson at 8 TeV with the ATLAS experiment

Mullier, Geoffrey; Haug, Sigve; Weber, Michael; Meloni, Federico; Cervelli, Alberto; Beck, Hans Peter; Stucci, Stefania; Ereditato, Antonio (2016). Measurement of the production cross-section of a single top quark in association with a W boson at 8 TeV with the ATLAS experiment. Journal of High Energy Physics, 2016(1) Springer 10.1007/JHEP01(2016)064

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The cross-section for the production of a single top quark in association with a W boson in proton--proton collisions at √s=8 TeV is measured. The dataset corresponds to an integrated luminosity of 20.3 fb⁻¹, collected by the ATLAS detector in 2012 at the Large Hadron Collider at CERN. Events containing two leptons and one central b-jet are selected. The Wt signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of Wt events is observed with a significance of 7.7σ . The cross-section is extracted in a profile likelihood fit to the classifier output distributions. The Wt cross-section, inclusive of decay modes, is measured to be 23.0±1.3 (stat.) +3.2 −3.5 (syst.)±1.1 (lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element |V tb| of 1.01±0.10 and a lower limit of 0.80 at the 95% confidence level. The cross-section for the production of a top quark and a W boson is also measured in a fiducial acceptance requiring two leptons with p T >25 GeV and |η|<2.5 , one jet with p T >20 GeV and |η|<2.5 , and E miss T >20 GeV, including both Wt and top-quark pair events as signal. The measured value of the fiducial cross-section is 0.85±0.01 (stat.) +0.06 −0.07 (syst.)±0.03 (lumi.) pb.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Laboratory for High Energy Physics (LHEP)

UniBE Contributor:

Haug, Sigve; Weber, Michael and Beck, Hans Peter

Subjects:

500 Science > 530 Physics
500 Science > 510 Mathematics

ISSN:

1029-8479

Publisher:

Springer

Language:

English

Submitter:

Annette Krebs-Wegenast

Date Deposited:

15 Aug 2017 09:31

Last Modified:

20 Aug 2017 02:17

Publisher DOI:

10.1007/JHEP01(2016)064

Additional Information:

Kollaboration - Es sind nur die Berner Autoren namentlich erwähnt.

BORIS DOI:

10.7892/boris.100008

URI:

https://boris.unibe.ch/id/eprint/100008

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