ATLAS collaboration (2857 authors)Aguilar-Saavedra, Juan AntonioAmor Dos Santos, Susana PatriciaAnjos, NunoAraque, Juan PedroCantrill, RobertCarvalho, JoãoCastro, Nuno FilipeConde Muiño, PatriciaDa Cunha Sargedas De Sousa, Mario JoseFiolhais, MiguelGalhardo, BrunoGomes, AgostinhoGonçalo, RicardoJorge, PedroLopes, LourencoMachado Miguens, JoanaMaio, AméliaManeira, JoséOnofre, AntónioPalma, AlbertoPedro, RutePina, João AntonioSantos, HelenaSaraiva, JoãoSilva, JoséTavares Delgado, AdemarVeloso, FilipeWolters, Helmut2019-02-042019-02-042016-01-07http://dx.doi.org/10.1140/epjc/s10052-015-3852-4http://hdl.handle.net/10400.26/26912Fiducial 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.engjournal article2019-02-04