Date of this Version
Physics Letters B 776 (2018) 355–378
The cross sections for the production of ttbb and ttjj events and their ratio σttbb/σttjj are measured using data corresponding to an integrated luminosity of 2.3fb−1 collected in pp collisions at √s = 13 TeV with the CMS detector at the LHC. Events with two leptons (e or μ) and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. In the full phase space, the measured ratio is 0.022 ± 0.003(stat) ± 0.006(syst), the cross section σttbb is 4.0 ± 0.6(stat) ±1.3(syst) pb and σttjj is 184 ± 6(stat) ± 33(syst) pb. The measurements are compared with the standard model expectations obtained from a powheg simulation at next-to-leading-order interfaced with pythia.