# Measurements of fiducial cross-sections for $t\bar{t}$ production with one or two additional $b$-jets in $pp$ collisions at $\sqrt{s}$ = 8 TeV using the ATLAS detector

Abstract : Fiducial cross-sections for $t\bar{t}$ production with one or two additional $b$-jets are reported, using an integrated luminosity of 20.3 fb$^{-1}$ of proton--proton collisions at a centre-of-mass energy of 8 TeV at the Large Hadron Collider, collected with the ATLAS detector. The cross-section times branching ratio for $t\bar{t}$ events with at least one additional $b$-jet is measured to be 950 $\pm$ 70 (stat.) $^{+240}_{-190}$ (syst.) fb in the lepton-plus-jets channel and 50 $\pm$ 10 (stat.) $^{+15}_{-10}$ (syst.) fb in the $e \mu$ channel. The cross-section times branching ratio for events with at least two additional $b$-jets is measured to be 19.3 $\pm$ 3.5 (stat.) $\pm$ 5.7 (syst.) fb in the dilepton channel ($e \mu$,\,$\mu\mu$, and \,$ee$) using a method based on tight selection criteria, and 13.5 $\pm$ 3.3 (stat.) $\pm$ 3.6 (syst.) fb using a looser selection that allows the background normalisation to be extracted from data. The latter method also measures a value of 1.30 $\pm$ 0.33 (stat.) $\pm$ 0.28 (syst.)\% for the ratio of $t\bar{t}$ production with two additional $b$-jets to $t\bar{t}$ production with any two additional jets. All measurements are in good agreement with recent theory predictions.
Type de document :
Article dans une revue
European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2016, 76, pp.11. 〈10.1140/epjc/s10052-015-3852-4〉

http://hal.in2p3.fr/in2p3-01187948
Contributeur : Claudine Bombar <>
Soumis le : vendredi 28 août 2015 - 11:04:48
Dernière modification le : lundi 22 octobre 2018 - 09:42:01

### Citation

G. Aad, Z. Barnovska, N. Berger, M. Delmastro, L. Di Ciaccio, et al.. Measurements of fiducial cross-sections for $t\bar{t}$ production with one or two additional $b$-jets in $pp$ collisions at $\sqrt{s}$ = 8 TeV using the ATLAS detector. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2016, 76, pp.11. 〈10.1140/epjc/s10052-015-3852-4〉. 〈in2p3-01187948〉

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