Measurement of the ZZ production cross section and Z → ℓ+ℓ−ℓ′+ℓ′− branching fraction in pp collisions at s=13TeV

Four-lepton production in proton-proton collisions, pp→(Z/γ⁎)(Z/γ⁎)→ℓ+ℓ−ℓ′+ℓ′−, where ℓ,ℓ′=e or μ, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.6 fb−1. The ZZ production cross section, σ(pp→ZZ)=14.6−1.8+1.9(stat)−0.3+0.5(syst)±0.2(theo)±0.4(lumi)pb, is measured for events with two opposite-sign, same-flavor lepton pairs produced in the mass region 604GeV for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.