Measurement of the $\textrm{pp} \rightarrow \textrm{Z}\textrm{Z}$ production cross section at $\sqrt{s} = 13$ TeV with the Run 2 data set

Four-lepton production in proton-proton collisions, $\textrm{pp} \rightarrow (\textrm{Z}/\gamma^*)(\textrm{Z}/\gamma^*) \rightarrow 4\ell$, where $\ell$ = e or $\mu$, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data samples correspond to integrated luminosities of 41.5 and 59.7 fb$^{-1}$, collected in 2017 and 2018 running periods respectively. By combining the 2017 and 2018 results with the previously published 2016 results, the ZZ production cross section is measured, $\sigma_{tot} ( \textrm{pp} \rightarrow \textrm{ZZ} ) = 17.1 \pm 0.3 (\textrm{stat}) \pm 0.4 (\textrm{syst}) \pm 0.4 (\textrm{theo}) \pm 0.3 (\textrm{lumi})$ pb, for events with two opposite-sign, same-flavor lepton pairs produced in the mass region $60 < m_{\ell^+\ell^-} < 120$ GeV. The measured cross section value is consistent with standard model predictions.