Measurement of top quark pair production in association with a Z boson in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A measurement of the cross section of top quark pair production in association with a Z boson using proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC is performed. The data sample corresponds to an integrated luminosity of $77.5~\textrm{fb}^{-1}$, collected by the CMS experiment during 2016 and 2017. The measurement is performed in the three- and four-lepton final states. The production cross section is measured to be $\sigma(\mathrm{t}\overline{\mathrm{t}}\mathrm{Z})=1.00~^{+0.06}_{-0.05}\,\mathrm{ (stat) }\,^{+0.07}_{-0.06}\,\mathrm{ (syst)}$ pb. Differential cross sections are measured as a function of the transverse momentum of the Z boson and the angular distribution of the decay lepton. New stringent limits on the anomalous couplings of the top quark to the Z boson are obtained, including estimates of Wilson coefficients of standard model effective field theory.