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 |Vtb| 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 pT> 25 GeV and |η| < 2.5, one jet with pT> 20 GeV and |η| < 2.5, and ETmiss > 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.

Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Aben, R., Abolins, M., et al. (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), 1-48 [10.1007/JHEP01(2016)064].

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

BELLAGAMBA, LORENZO;BIONDI, SILVIA;BOSCHERINI, DAVIDE;BRUNI, ALESSIA;BRUNI, GRAZIANO;DE CASTRO, STEFANO;FABBRI, LAURA;FRANCHINI, MATTEO;GABRIELLI, ALESSANDRO;GIACOBBE, BENEDETTO;LASAGNI MANGHI, FEDERICO;MASSA, LORENZO;MENGARELLI, ALBERTO;POLINI, ALESSANDRO;RINALDI, LORENZO;ROMANO, MARINO;SBARRA, CARLA;SEMPRINI CESARI, NICOLA;SIOLI, MAXIMILIANO;SPIGHI, ROBERTO;VALENTINETTI, SARA;VILLA, MAURO;Vivarelli, I.;ZOCCOLI, ANTONIO;
2016

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 |Vtb| 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 pT> 25 GeV and |η| < 2.5, one jet with pT> 20 GeV and |η| < 2.5, and ETmiss > 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.
2016
Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Aben, R., Abolins, M., et al. (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), 1-48 [10.1007/JHEP01(2016)064].
Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; Abouzeid, O.S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B....espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/588377
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