CMS collaboration (2269 authors)Calpas, BettyNayak, ArunaBargassa, PedrameBeirão Da Cruz E Silva, CristóvãoDi Francesco, AgostinoFaccioli, PietroFerreira Parracho, Pedro GuilhermeGallinaro, MicheleHollar, JonathanLeonardo, NunoLloret Iglesias, LaraRodrigues Antunes, JoaoSeixas, JoaoToldaiev, OleksiiVadruccio, DanieleVarela, JoaoVischia, PietroDavid Tinoco Mendes, AndreSilva, PedroMusella, PasqualePela, Joao2019-02-042019-02-042016-12-10http://dx.doi.org/10.1016/j.physletb.2016.10.054, 10.1016/j.physletb.2017.09.030http://hdl.handle.net/10400.26/27153Four-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 60<mℓ+ℓ−,mℓ′+ℓ′−<120 GeV . The Z boson branching fraction to four leptons is measured to be B(Z→ℓ+ℓ−ℓ′+ℓ′−)=4.9−0.7+0.8 (stat)−0.2+0.3 (syst)−0.1+0.2(theo)±0.1(lumi)×10−6 for the four-lepton invariant mass in the range 80<mℓ+ℓ−ℓ′+ℓ′−<100 GeV and dilepton mass mℓ+ℓ−>4 GeV for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.engjournal article2019-02-04