Differential and double-differential cross sections for the production of top quark pairs in proton-proton collisions at 13 TeV are measured as a function of jet multiplicity and of kinematic variables of the top quarks and the top quark-antiquark system. This analysis is based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 2.3 fb −1 . The measurements are performed in the lepton+jets decay channels with a single muon or electron in the final state. The differential cross sections are presented at particle level, within a phase space close to the experimental acceptance, and at parton level in the full phase space. The results are compared to several standard model predictions. Published in Physical Review D asIt should be remarked that events with a hadronic and a leptonic particle-level top quark are not required to be +jets events at the parton level. As an example, in Fig. 1 the relation between the p T (t h ) values at particle and parton level is shown. The CMS detectorThe central feature of the CMS detector is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter (HCAL), each composed of a barrel and two endcap sections. Forward calorimeters extend the η coverage provided by the barrel and endcap detectors. Muons C The CMS Collaboration

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 ffiffi ffi s p ¼ 8 TeV in data corresponding to an integrated luminosity of 19.7 fb −1 . The measurement is performed using lepton þ 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 tt ¼ 0.499 AE 0.035ðstat þ systÞ AE 0.095ðtheoÞ AE 0.013ðlumiÞ pb for top quark p T > 400 GeV. The parton-level measurement is σ tt ¼ 1.44 AE 0.10ðstat þ systÞ AE 0.29ðtheoÞ AE 0.04ðlumiÞ pb. The integrated and differential cross section results are compared to predictions from several event generators.

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