Fiducial cross-sections for tˉt 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 tˉt events with at least one additional b-jet is measured to be 950 ± 70 (stat.) +240−190 (syst.) fb in the lepton-plus-jets channel and 50 ± 10 (stat.) +15−10 (syst.) fb in the eμ channel. The cross-section times branching ratio for events with at least two additional b-jets is measured to be 19.3 ± 3.5 (stat.) ± 5.7 (syst.) fb in the dilepton channel (eμ, μμ, and ee) using a method based on tight selection criteria, and 13.5 ± 3.3 (stat.) ± 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 ± 0.33 (stat.) ± 0.28 (syst.)% for the ratio of tˉt production with two additional b-jets to tˉt production with any two additional jets. All measurements are in good agreement with recent theory predictions.
The European physical journal C. 2016. Vol. 76, № 1. P. 11 (1-37)
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Радиофизический факультет
Measurements of fiducial cross-sections for t t ¯ production with one or two additional b-jets in pp collisions at √s = 8 TeV using the ATLAS detector
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