Abstract
A measurement of the top quark-antiquark pair production cross section σtt¯ in proton-proton collisions at a centre-of-mass energy of 13 Te is presented. The data correspond to an integrated luminosity of 35.9 fb-1 , recorded by the CMS experiment at the CERN LHC in 2016. Dilepton events ( e ± μ ∓ , μ+μ- , e+e- ) are selected and the cross section is measured from a likelihood fit. For a top quark mass parameter in the simulation of mtMC = 172.5 Ge the fit yields a measured cross section σtt¯ = 803 ± 2 (stat) ± 25 (syst) ± 20 (lumi) pb , in agreement with the expectation from the standard model calculation at next-to-next-to-leading order. A simultaneous fit of the cross section and the top quark mass parameter in the powheg simulation is performed. The measured value of mtMC = 172.33 ± 0.14 (stat) -0.72+0.66 (syst) Ge is in good agreement with previous measurements. The resulting cross section is used, together with the theoretical prediction, to determine the top quark mass and to extract a value of the strong coupling constant with different sets of parton distribution functions.