Measurement of the pp → ZZ production cross section and constraints on anomalous triple gauge couplings in four-lepton final states at √s = 8 TeV

Abstract

A measurement of the inclusive ZZ production cross section and constraints on anomalous triple gauge couplings in proton–proton collisions at √s = 8 TeV are presented. The analysis is based on a data sample, corresponding to an integrated luminosity of 19.6 fb[superscript −1], collected with the CMS experiment at the LHC. The measurements are performed in the leptonic decay modes ZZ→ℓℓℓ′ℓ′, where ℓ=e,μ and ℓ′=e,μ,τ. The measured total cross section σ(pp→ZZ)=7.7±0.5 (stat)[+0.5 over −0.4](syst)±0.4(theo)±0.2 (lumi) pb, for both Z bosons produced in the mass range 60<[subscript mZ] <120 GeV60<mZ<120 GeV, is consistent with standard model predictions. Differential cross sections are measured and well described by the theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZγ couplings at the 95% confidence level: −0.004 < f[Z over 4] <0.004, −0.004 < f[Z over 5] < 0.004, −0.005 < f[γ over 4] < 0.005, and −0.005 < f[γ over 5] < 0.005.