The cross section for pair production of top quarks (tt¯) with high transverse momenta is measured in pp collisions, collected with the CMS detector at the LHC with √s = 8 TeV in data corresponding to an integrated luminosity of 19.7 fb−1. The measurement is performed using lepton + jets events, where one top quark decays semileptonically, while the second top quark decays to a hadronic final state. The hadronic decay is reconstructed as a single, large-radius jet, and identified as a top quark candidate using jet substructure techniques. The integrated cross section and the differential cross sections as a function of top quark pT and rapidity are measured at particle level within a fiducial region related to the detector-level requirements and at parton level. The particle-level integrated cross section is found to be σtt¯ = 0.499 ± 0.035(stat + syst) ±0.095(theo) ±0.013(lumi) pb for top quark pT > 400 GeV. The parton-level measurement is σtt¯ = 1.44 ± 0.10(stat + syst) ± 0.29(theo) ± 0.04(lumi) pb. The integrated and differential cross section results are compared to predictions from several event generators.
- Proton–proton collisions