Evidence of ZZγ Production and Observation of 4ℓγ in Proton-Proton Collisions at sqrt[s]=13 TeV


Hayrapetyan A., Makarenko V., Tumasyan A., Adam W., Benato L., Bergauer T., ...More

Physical review letters, vol.137, no.9, pp.91805, 2026 (SCI-Expanded, Scopus)

  • Publication Type: Article / Article
  • Volume: 137 Issue: 9
  • Publication Date: 2026
  • Doi Number: 10.1103/gdbv-wnpp
  • Journal Name: Physical review letters
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, EMBASE, INSPEC, MathSciNet, MEDLINE, zbMATH, DIALNET
  • Page Numbers: pp.91805
  • Istanbul University Affiliated: Yes

Abstract

Evidence of the production of two Z bosons and a photon in proton-proton collisions is reported for the first time in CMS. The analysis uses data collected by the CMS experiment between 2016 and 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb^{-1}. Evidence for the process pp→ZZγ→4ℓγ (ℓ=e, μ), with an observed (expected) significance of 3.7 (3.1) standard deviations in a fiducial region defined by p_{T}^{γ}>20 GeV, |η^{γ}|<2.4, ΔR(ℓ,γ)>0.5, m_{Z} between 60 and 120 GeV, and the invariant mass of either of the two Z bosons combined with the photon (m_{Z_{γ}}) larger than 100 GeV, is reported. The measured (predicted) fiducial cross section is 60_{-22}^{+27} ab (47.56±0.04 ab). Additionally, the inclusive production of pp→4ℓγ is studied by removing the m_{Z_{γ}} requirement to include final state radiation where one Z boson decays to 2ℓγ, yielding an observed (expected) significance of 5.0 (4.2) standard deviations and a measured (predicted) fiducial cross section of 156_{-35}^{+39} ab (99.97±0.09 ab).