Abstract:
The first measurement of the cross section ratio \(\sigma_{t\overline{t}b\overline{b}}\) / \(\sigma_{t\overline{t}jj}\) is presented using a data sample corresponding to an integrated luminosity of 19.6 fb⁻¹ collected in pp collisions at \(\sqrt{s}\)=8TeV with the CMS detector at the LHC. Events with two leptons (e or \(\mu\)) and four reconstructed jets, including two identified as b quark jets, in the final state are selected. The ratio is determined for a minimum jet transverse momentum \(p_T\) of both 20 and 40 GeV/ c. The measured ratio is 0.022±0.003(stat)±0.005(syst) for \(p_T\)>20 GeV/c. The absolute cross sections \(\sigma_{t\overline{t}b\overline{b}}\) and \(\sigma_{t\overline{t}jj}\) are also measured. The measured ratio for \(p_T\)>40 GeV/c is compatible with a theoretical quantum chromodynamics calculation at next-to-leading order.
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