Measurement of the cross section ratio ttbar+bbbar/ttbar+jj using dilepton final states in pp collisions at 13 TeV

The measurement of the cross section ratio $ \sigma_{\rm t\bar{t}b\bar{b}} $ / $ \sigma_{\rm t\bar{t}jj} $ is presented using a data sample corresponding to an integrated luminosity of 2.3 $\rm{fb}^{-1}$ collected in pp collisions at $\sqrt{s}$ = 13 TeV with the CMS detector at the LHC. Events with two leptons (${\rm e}$ or $\mu$) and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. The measured ratio is $0.022 \pm 0.003~{\rm (stat)} \pm0.006~{\rm (syst)}$ and cross section $ \sigma_{\rm t\bar{t}b\bar{b}} $ is $3.9 \pm 0.6~{\rm (stat)} \pm1.3~{\rm (syst)}$ pb and $ \sigma_{\rm t\bar{t}jj} $ is $176 \pm 5~{\rm (stat)} \pm 33~{\rm (syst)}$ pb in the full phase space. The measurement is compatible with the expectation obtained from the POWHEG simulation interfaced with PYTHIA.