Precise measurement of the tt ̄ production cross-section and lepton differential distributions in eμ dilepton events from s=13TeVpp collisions with the ATLAS detector

The inclusive top quark pair (tt¯) cross-section σtt¯ has been measured in proton–proton collisions at s=13TeV, using 140fb-1 of data collected by the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge eμ pair and b-tagged jets, the cross-section is measured to be: (Formula presented.) where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the proton beam energy, giving a total uncertainty of 1.3%. The result is used to determine the top quark pole mass via the dependence of the predicted cross-section on mtpole, giving mtpole=172.8-1.7+1.5 GeV. The same event sample is used to measure absolute and normalised differential cross-sections for the tt¯→eμνν¯bb¯ process as a function of single-lepton and dilepton kinematic variables. Complementary measurements of eμbb¯ production, treating both tt¯ and Wt events as signal, are also provided. Both sets of differential cross-sections are compared to the predictions of various Monte Carlo event generators, demonstrating that the state-of-the-art generators Powheg MiNNLO and Powhegbb4l describe the data better than Powheghvq.