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

Barton, Adam Edward and Beattie, Michael and Borissov, Guennadi and Bouhova-Thacker, Evelina Vassileva and Dearnaley, William and Fox, Harald and Grimm, Kathryn Ann Tschann and Henderson, Robert Charles William and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin Eamonn and Love, Peter Allan and Maddocks, Harvey and Skinner, Malcolm and Smizanska, Maria and Walder, James William and Wharton, Andy (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). ISSN 1029-8479

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Abstract

The cross-section for the production of a single top quark in association with a W boson in proton-proton collisions at √s=8TeV 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 W t signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of W t 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 W t cross-section, inclusive of decay modes, is measured to be 23.0 ± 1.3(stat.) − 3.5 + 3.2 (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 T miss  > 20 GeV, including both W t and top-quark pair events as signal. The measured value of the fiducial cross-section is 0.85 ± 0.01(stat.) − 0.07 + 0.07 (syst.)±0.03(lumi.) pb.

Item Type: Journal Article
Journal or Publication Title: Journal of High Energy Physics
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/3100/3106
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 78895
Deposited By: ep_importer_pure
Deposited On: 01 Apr 2016 09:26
Refereed?: Yes
Published?: Published
Last Modified: 21 Oct 2019 00:39
URI: https://eprints.lancs.ac.uk/id/eprint/78895

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