Measurement of the ZZ production cross section and Z to l+l-l'+l'- branching fraction in pp collisions at sqrt(s) = 13 TeV

TL;DR

This paper reports the measurement of the ZZ production cross section and Z boson to four-lepton branching fraction in proton-proton collisions at 13 TeV, confirming consistency with the Standard Model predictions.

Contribution

First measurement of ZZ production cross section and Z to four-lepton branching fraction at 13 TeV with CMS detector data.

Findings

Measured sigma(pp to ZZ) = 14.6 pb with uncertainties.

Measured Z to 4 leptons branching fraction as 4.9 x 10^-6.

Results agree with Standard Model predictions.

Abstract

Four-lepton production in proton-proton collisions, pp to (Z/gamma*)(Z/gamma*) to l+l-l'+l'-, where l, l' = e or mu, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.6 inverse femtobarns. The ZZ production cross section, sigma(pp to ZZ) = 14.6 +1.9/-1.8 (stat) +0.5/-0.3 (syst) +/- 0.2 (theo) +/- 0.4 (lumi) pb, is measured for events with two opposite-sign, same-flavor lepton pairs produced in the mass region 60 < m[l+l-], m[l'+l'-] < 120 GeV. The Z boson branching fraction to four leptons is measured to be B(Z to l+l-l'+l'-) = 4.9 +0.8/-0.7 (stat) +0.3/-0.2 (syst) +0.2/-0.1 (theo) +/- 0.1 (lumi) x E-6 for the four-lepton invariant mass in the range 80 < m[l+l-l'+l'-] < 100 GeV and dilepton mass m[l+l-] > 4 GeV for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.