Measurements of pp $\to$ ZZ production cross sections and constraints on anomalous triple gauge couplings at $\sqrt{s} =$ 13 TeV

TL;DR

This study measures the ZZ production cross section in proton-proton collisions at 13 TeV using CMS data, confirming consistency with the Standard Model and setting limits on anomalous gauge couplings.

Contribution

First precise measurement of ZZ production cross section at 13 TeV with differential analysis and constraints on anomalous triple gauge couplings.

Findings

Measured total ZZ cross section: 17.2 pb with uncertainties.

Differential cross sections agree with theoretical predictions.

Set limits on anomalous ZZZ and ZZγ couplings.

Abstract

The production of Z boson pairs in proton-proton (pp) collisions, pp $\to$ (Z/$\gamma^*$)(Z/$\gamma^*$) $\to$ 2$\ell$ 2$\ell'$, where $\ell,\ell'$ = e or $\mu$, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137 fb$^{-1}$, collected during 2016-2018. The ZZ production cross section, $\sigma_{\text{tot}}$ (pp $\to$ ZZ) = 17.2 $\pm$ 0.3 (stat) $\pm$ 0.5 (syst) $\pm$ 0.4 (theo) $\pm$ 0.3 (lumi) pb, measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region 60 $\lt$ $m_{\ell^+\ell^-}$ $\lt $ 120 GeV is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZ$\gamma$ couplings.