# Measurement of the ZZ production cross section and $Z \to \ell^⁺\ell^⁻\ell'^⁺\ell'^⁻$ branching fraction in pp collisions at $\sqrt{s} = 13$ TeV

CMS Collaboration; Canelli, Florencia; Kilminster, Benjamin; Aarestad, Thea; Caminada, Lea; De Cosa, Annapaoloa; Del Burgo, Riccardo; Donato, Silvio; Galloni, Camilla; Hinzmann, Andreas; Hreus, Tomas; Ngadiuba, Jennifer; Pinna, Deborah; Rauco, Giorgia; Robmann, Peter; Salerno, Daniel; Schweiger, Korbinian; Seitz, Claudia; Takahashi, Yuta; Zucchetta, Alberto; et al (2016). Measurement of the ZZ production cross section and $Z \to \ell^⁺\ell^⁻\ell'^⁺\ell'^⁻$ branching fraction in pp collisions at $\sqrt{s} = 13$ TeV. Physics Letters B, B763:280-303.

## Abstract

Four-lepton production in proton–proton collisions, $pp→(Z/γ⁎)(Z/γ⁎)→ℓ^+ℓ^−ℓ'^+ℓ'^−$, where $ℓ,ℓ′=e$ or $μ$, 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 $fb^{-1}$. The ZZ production cross section, $σ(pp→ZZ)=14.6^{+1.9}_{-1.8}(stat)^{+0.5}_{−0.3}(syst)±0.2(theo)±0.4(lumi)pb$, is measured for events with two opposite-sign, same-flavor lepton pairs produced in the mass region $60<m_{ℓ^+ℓ^−},m_{ℓ'^+ℓ'^−}<120GeV$. The Z boson branching fraction to four leptons is measured to be $\mathcal{B}(Z→ℓ^+ℓ^−ℓ'^+ℓ'^−)=4.9^{+0.8}_{−0.7} (stat)^{+0.3}_{−0.2} (syst)+0.2−0.1(theo)±0.1(lumi)×10^{−6}$ for the four-lepton invariant mass in the range $80<m_{ℓ^+ℓ^−ℓ'^+ℓ'^−}<100GeV$ and dilepton mass $m_{ℓ^+ℓ^-}>4GeV$ for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.

## Abstract

Four-lepton production in proton–proton collisions, $pp→(Z/γ⁎)(Z/γ⁎)→ℓ^+ℓ^−ℓ'^+ℓ'^−$, where $ℓ,ℓ′=e$ or $μ$, 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 $fb^{-1}$. The ZZ production cross section, $σ(pp→ZZ)=14.6^{+1.9}_{-1.8}(stat)^{+0.5}_{−0.3}(syst)±0.2(theo)±0.4(lumi)pb$, is measured for events with two opposite-sign, same-flavor lepton pairs produced in the mass region $60<m_{ℓ^+ℓ^−},m_{ℓ'^+ℓ'^−}<120GeV$. The Z boson branching fraction to four leptons is measured to be $\mathcal{B}(Z→ℓ^+ℓ^−ℓ'^+ℓ'^−)=4.9^{+0.8}_{−0.7} (stat)^{+0.3}_{−0.2} (syst)+0.2−0.1(theo)±0.1(lumi)×10^{−6}$ for the four-lepton invariant mass in the range $80<m_{ℓ^+ℓ^−ℓ'^+ℓ'^−}<100GeV$ and dilepton mass $m_{ℓ^+ℓ^-}>4GeV$ for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.

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## Additional indexing

Item Type: Journal Article, refereed, original work 07 Faculty of Science > Physics Institute 530 Physics English 2016 18 Dec 2017 10:51 18 Dec 2017 15:56 Elsevier 0370-2693 Erratum: Phys. Lett.B772,884(2017) http://10.1016/j.physletb.2017.09.030 Publisher DOI. An embargo period may apply. https://doi.org/10.1016/j.physletb.2016.10.054 http://www.zora.uzh.ch/id/eprint/143507/

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