Measurement of the cross section ratio sigma(t(t)over-barb(b)over-bar)/sigma(t(t)over-barjj) in pp collisions at root s=8 TeV

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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.

CMS, Physics, Top physics, Astronomy & Astrophysics, Physics, Nuclear, Physics, Particles & Fields
Khachatryan, V., Sirunyan, A. M., Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Erö, J., Fabjan, C., Friedl, M., Frühwirth, R., Ghete, V. M., Hartl, C., Hörmann, N., Hrubec, J., Jeitler, M., Kiesenhofer, W., Knünz, V., Krammer, M., Krätschmer, I., … Woods, N. (2015). Measurement of the cross section ratio σtt¯bb¯/σtt¯jj in pp collisions at $\sqrt{s}$=8TeV. In Physics Letters B (Vol. 746, pp. 132–153). Elsevier BV.