Measurement of the $ZZ$ production cross section in proton-proton collisions at $\sqrt s =$ 8 TeV using the $ZZ\to\ell^{-}\ell^{+}\ell^{\prime -}\ell^{\prime +}$ and $ZZ\to\ell^{-}\ell^{+}\nu\bar{\nu}$ channels with the ATLAS detector

A measurement of the ZZ production cross section in the ℓ$^{−}$ℓ$^{+}$ℓ$^{′ −}$ℓ$^{′ +}$ and $ {\ell}^{-}{\ell}^{+}\nu \overline{\nu} $ channels (ℓ = e, μ) in proton-proton collisions at $ \sqrt{s}=8 $ TeV at the Large Hadron Collider at CERN, using data corresponding to an integrated luminosity of 20.3 fb$^{−1}$ collected by the ATLAS experiment in 2012 is presented. The fiducial cross sections for ZZ → ℓ$^{−}$ℓ$^{+}$ℓ$^{′ −}$ℓ$^{′ +}$ and $ ZZ\to {\ell}^{-}{\ell}^{+}\nu \overline{\nu} $ are measured in selected phase-space regions. The total cross section for ZZ events produced with both Z bosons in the mass range 66 to 116 GeV is measured from the combination of the two channels to be 7.3 ± 0.4(stat) ± 0.3(syst)$_{− 0.1}^{− 0.2}$ (lumi) pb, which is consistent with the Standard Model prediction of 6. 6$_{− 0.6}^{+ 0.7}$ pb. The differential cross sections in bins of various kinematic variables are presented. The differential event yield as a function of the transverse momentum of the leading Z boson is used to set limits on anomalous neutral triple gauge boson couplings in ZZ production.