Measurement of the integrated and differential t ¯ t production cross sections for high- p T top quarks in p p collisions at √ s = 8 TeV

Abstract

The cross section for pair production of top quarks ( t ¯ t ) with high transverse momenta is measured in p p 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 p T 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 σ t ¯ t = 0.499 ± 0.035 ( stat + syst ) ± 0.095 ( theo ) ± 0.013 ( lumi ) pb for top quark p T > 400 GeV . The parton-level measurement is σ t ¯ t = 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.