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

G. Aad 1 S. Albrand 2 J. Collot 2 S. Crépé-Renaudin 2 P.A. Delsart 2 C. Gabaldon 2 M.H. Genest 2 J.Y. Hostachy 2 F. Ledroit-Guillon 2 A. Lleres 2 A. Lucotte 2 F. Malek 2 C. Monini 2 J. Stark 2 B. Trocmé 2 M. Wu 2 G. Rahal 3 M.K. Ayoub 4 A. Bassalat 4 C. Bécot 4 S. Binet 4 C. Bourdarios 4 D. Delgove 4 J-B. de Vivie De Regie 4 L. Duflot 4 M. Escalier 4 L. Fayard 4 D. Fournier 4 E.L. Gkougkousis 4 J-F. Grivaz 4 T. Guillemin 4 F. Hariri 4 S. Henrot-Versille 4 J. Hrivnac 4 L. Iconomidou-Fayard 4 M. Kado 4 A. Lounis 4 N. Makovec 4 N. Morange 4 C. Nellist 4 P. Petroff 4 L. Poggioli 4 P. Puzo 4 A. Renaud 4 D. Rousseau 4 G. Rybkin 4 A.C. Schaffer 4 E. Scifo 4 L. Serin 4 S. Simion 4 R. Tanaka 4 D. Zerwas 4 Zhongkai Zhang 4 Y. Zhao 4 Z. Barnovska 5 N. Berger 5 M. Delmastro 5 L. Di Ciaccio 5 S. Elles 5 C. Goy 5 T. Hryn’ova 5 S. Jézéquel 5 I. Koletsou 5 R. Lafaye 5 J. Levêque 5 N. Massol 5 P. Mastrandea 5 G. Sauvage 5 E. Sauvan 5 O. Simard 5 T. Todorov 5 I. Wingerter-Seez 5 E. Yatsenko 5 D. Boumediene 6 E. Busato 6 D. Calvet 6 S. Calvet 6 J. Donini 6 E. Dubreuil 6 N. Ghodbane 6 G. Gilles 6 Ph. Gris 6 C. Guicheney 6 H. Liao 6 D. Pallin 6 F. Podlyski 6 C. Santoni 6 D. Simon 6 T. Theveneaux-Pelzer 6 L. Valéry 6 F. Vazeille 6 L. Alio 1 M. Barbero 1 Y. Coadou 1 C. Diaconu 1 S. Diglio 1 F. Djama 1 L. Feligioni 1 J. Gao 1 G.D. Hallewell 1 F. Hubaut 1 S.J. Kahn 1 E.B.F.G. Knoops 1 E. Le Guirriec 1 J. Liu 1 K. Liu D. Madafari K. Mochizuki 1 E. Monnier 1 S. Muanza 1 Y. Nagai 1 E. Nagy 1 P. Pralavorio 1 A. Rozanov 1 T. Serre 1 M. Talby 1 R.E. Ticse Torres 1 E. Tiouchichine 1 S. Tisserant 1 J. Toth 1 F. Touchard 1 L. Vacavant 1
Abstract : The cross-section for the production of a single top quark in association with a $W$ boson in proton--proton collisions at $\sqrt{s}= 8$ 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 $7.7 \sigma$. 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 $23.0 \pm 1.3$(stat.)$^{+3.2}_{-3.5}$(syst.)$\pm 1.1$(lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element $|V_{tb}|$ of $1.01 \pm 0.10$ 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 $p_{\textrm{T}}>25$ GeV and $|\eta|<2.5$, one jet with $p_{\textrm{T}}>20$ GeV and $|\eta|<2.5$, and $E_{\textrm{T}}^{\textrm{miss}}>20$ GeV, including both $Wt$ and top-quark pair events as signal. The measured value of the fiducial cross-section is $0.85 \pm 0.01$(stat.)$^{+0.06}_{-0.07}$(syst.)$\pm 0.03$(lumi.) pb.
Type de document :
Article dans une revue
Journal of High Energy Physics, Springer Verlag (Germany), 2016, 01, pp.064. 〈10.1007/JHEP01(2016)064〉
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Soumis le : mercredi 14 octobre 2015 - 07:54:18
Dernière modification le : mercredi 16 mai 2018 - 15:10:07

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G. Aad, S. Albrand, J. Collot, S. Crépé-Renaudin, P.A. Delsart, et al.. 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, Springer Verlag (Germany), 2016, 01, pp.064. 〈10.1007/JHEP01(2016)064〉. 〈in2p3-01215349〉

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