Measurement of ZZ production in pp collisions at √ = 7 TeV and limits on anomalous ZZZ and ZZγ couplings with the ATLAS detector

Abstract

A measurement of the ZZ production cross section in proton-proton collisions at $ \sqrt{s}=7 $ TeV using data recorded by the ATLAS experiment at the Large Hadron Collider is presented. In a data sample corresponding to an integrated luminosity of 4.6 fb⁻¹ collected in 2011, events are selected that are consistent either with two Z bosons decaying to electrons or muons or with one Z boson decaying to electrons or muons and a second Z boson decaying to neutrinos. The ZZ ^(*) → ℓ ⁺ ℓ ⁻ ℓ ^′+ ℓ ^′− and $ ZZ\to {\ell^{+}}{\ell^{-}}\nu \overline{\nu} $ cross sections are measured in restricted phase-space regions. These results are then used to derive the total cross section for ZZ events produced with both Z bosons in the mass range 66 to 116 GeV, $ \sigma_{ZZ}^{\mathrm{tot}} = 6.7 \pm 0.7\;\,\left( {\mathrm{stat}.} \right)\;\;_{-0.3}^{+0.4}\;\,\left( {\mathrm{syst}.} \right) \pm 0.3\;\,\left( {\mathrm{lumi}.} \right) $ pb, which is consistent with the Standard Model prediction of $ 5.89_{-0.18}^{+0.22 } $ pb calculated at next-to-leading order in QCD. The normalized differential cross sections in bins of various kinematic variables are presented. Finally, 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.