Abstract
Measurements of $ZZ$ production in the $\ell^{+}\ell^{-}\ell^{\prime +}\ell^{\prime -}$ channel in proton-proton collisions at 13 TeV center-of-mass energy at the Large Hadron Collider are presented. The data correspond to 36.1 $\mathrm{fb}^{-1}$ of collisions collected by the ATLAS experiment in 2015 and 2016. Here $\ell$ and $\ell'$ stand for electrons or muons. Integrated and differential $ZZ \to \ell^{+}\ell^{-}\ell^{\prime +}\ell^{\prime -}$ cross sections with $Z \to \ell^+\ell^-$ candidate masses in the range of 66 GeV to 116 GeV are measured in a fiducial phase space corresponding to the detector acceptance and corrected for detector effects. The differential cross sections are presented in bins of twenty observables, including several that describe the jet activity. The integrated cross section is also extrapolated to a total phase space and to all Standard-Model decays of $Z$ bosons with mass between 66 GeV and 116 GeV, resulting in a value of $17.3 \pm 0.9$ [$\pm 0.6$ (stat.) $\pm 0.5$ (syst.) $\pm 0.6$ (lumi.)] pb. The measurements are found to be in good agreement with the Standard-Model predictions. A search for neutral triple gauge couplings is performed using the transverse momentum distribution of the leading $Z$-boson candidate. No evidence for such couplings is found and exclusion limits are set on their parameters.
Highlights
The study of the production of Z boson pairs in proton– proton interactions at the Large Hadron Collider (LHC) [1] tests the electroweak sector of the standard model (SM) at the highest available energies
It is a major background in searches for new physics processes producing pairs of Z bosons at high invariant mass [8,9,10,11] and it is sensitive to anomalous triple gauge couplings of neutral gauge bosons, which are not allowed in the SM [12]
The production of pairs of Z bosons is studied in the ZZ → lþl−l0þl0− channel in 13 TeV proton–proton collisions produced at the LHC and recorded with the ATLAS detector, using data corresponding to an integrated luminosity of 36.1 Æ 1.1 fb−1
Summary
The study of the production of Z boson pairs in proton– proton (pp) interactions at the Large Hadron Collider (LHC) [1] tests the electroweak sector of the standard model (SM) at the highest available energies. This paper represents an extension of the ATLAS measurement, using a total of 36.1 Æ 1.1 fb−1 of data collected with the ATLAS detector in the years 2015 and 2016 In this analysis, candidate events are reconstructed in the fully leptonic ZZ → lþl−l0þl0− decay channel where l and l0 can be an electron or a muon. A fiducial phase space is defined, reflecting both the acceptance of the ATLAS detector [22,23] and the selections imposed on the reconstructed leptons in this analysis Both the integrated and differential cross sections are measured, the latter with respect to 20 different observables. They both tend to have larger values in weakboson scattering than in other ZZ production channels, providing an important step towards the study of ZZ production via weak-boson scattering
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