  The cross section of top quark-antiquark pair production in proton-proton
collisions at sqrt(s) = 13 TeV is measured by the CMS experiment at the LHC,
using data corresponding to an integrated luminosity of 2.2 inverse femtobarns.
The measurement is performed by analyzing events in which the final state
includes one electron, one muon, and two or more jets, at least one of which is
identified as originating from hadronization of a b quark. The measured cross
section is 815 +/- 9 (stat) +/- 38 (syst) +/- 19 (lumi) pb, in agreement with
the expectation from the standard model.
