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

The inclusive top quark pair (tt) cross-section σt ¯t has been measured in proton–proton collisions at √s = 13 TeV, using 140 fb−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: σt ¯t = 829.3 ± 1.3 (stat) ± 8.0 (syst) ± 7.3 (lumi)±1.9 (beam) pb, 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 mpole t , giving mpole t = 172.8+1.5−1.7 GeV. The same event sample is used to measure absolute and normalised differential cross-sections for the t¯t → eμν ¯νb ¯b process as a function of single-lepton and dilepton kinematic
variables. Complementary measurements of eμb ¯b production, treating both t¯t and W t 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 Powheg bb4l describe the data better than Powheg hvq.