Measurement of ZZ production cross section in ZZ to 2l2l' decay channel in pp collisions at sqrt(s) = 8 TeV

A measurement of the ZZ production cross section in the ZZ $\rightarrow 2\ell 2\ell'$ decay mode with $\ell = e, \mu$ and $\ell' = e, \mu, \tau$ in proton-proton collisions at $\sqrt{s} = 8$~TeV is presented. Results are based on data corresponding to an integrated luminosity of 5.26 fb$^{-1}$ collected with the CMS experiment at the LHC. The measured cross section $\sigma ( pp \rightarrow $ZZ $) = 8.4 \pm 1.0(stat.) \pm 0.7 (sys.) \pm 0.4(lumi.)\, \rm{pb}$ for both Zs produced in the mass region $60 < m_{Z} < 120 $ GeV is consistent with the standard model prediction.