Measurement of the Associated Production of a Single Top Quark and a Z Boson in pp Collisions at √s = 13 TeV

A measurement is presented of the associated production of a single top quark and a Z boson. The study uses data from proton–proton collisions at √s = 13 TeV recorded by the CMS experiment, corresponding to an integrated luminosity of 35.9 fb^(−1). Using final states with three leptons (electrons or muons), the tZq production cross section is measured to be σ(pp→tZq→Wbl^+l^−q)=123_(−31)^(+33)(stat)_(−23)^(+29)(syst)fb, where l stands for electrons, muons, or τ leptons, with observed and expected significances of 3.7 and 3.1 standard deviations, respectively.