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.
| Original language | English (US) |
|---|---|
| Journal | European Physical Journal E |
| State | Published - Jan 7 2016 |