Abstract
AbstractA measurement of theZZproduction cross section in proton-proton collisions at$ \sqrt{s}=7 $TeV using data recorded by the ATLAS experiment at the Large Hadron Collider is presented. In a data sample corresponding to an integrated luminosity of 4.6 fb−1collected in 2011, events are selected that are consistent either with twoZbosons decaying to electrons or muons or with oneZboson decaying to electrons or muons and a secondZboson decaying to neutrinos. TheZZ(*)→ℓ+ℓ−ℓ′+ℓ′−and$ ZZ\to {\ell^{+}}{\ell^{-}}\nu \overline{\nu} $cross sections are measured in restricted phase-space regions. These results are then used to derive the total cross section forZZevents produced with bothZbosons in the mass range 66 to 116 GeV,$ \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 leadingZboson is used to set limits on anomalous neutral triple gauge boson couplings inZZproduction.
Highlights
The production of pairs of Z bosons at the Large Hadron Collider (LHC) provides an excellent opportunity to test the predictions of the electroweak sector of the Standard
The results presented in this paper supersede the previously published results [13] which were derived with the first 1.02 fb−1 of the dataset used here, only with the ZZ → + − + − decay channel and with the use of the total ZZ event count for the derivation of the limits on anomalous neutral triple gauge boson couplings (nTGCs)
The total cross section for non-resonant ZZ production is predicted at next-to-leading order (NLO) in QCD to be 6.18+−00..2158 pb, where the quoted theoretical uncertainties result from varying the factorization and renormalization scales simultaneously by a factor of two whilst using the full CT10 parton distribution function (PDF) error set [19]
Summary
The production of pairs of Z bosons at the Large Hadron Collider (LHC) provides an excellent opportunity to test the predictions of the electroweak sector of the Standard. The results presented in this paper supersede the previously published results [13] which were derived with the first 1.02 fb−1 of the dataset used here, only with the ZZ → + − + − decay channel and with the use of the total ZZ event count for the derivation of the limits on anomalous nTGCs. The total cross section for non-resonant ZZ production is predicted at next-to-leading order (NLO) in QCD to be 6.18+−00..2158 pb, where the quoted theoretical uncertainties result from varying the factorization and renormalization scales simultaneously by a factor of two whilst using the full CT10 parton distribution function (PDF) error set [19].
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