The first observation of the electroweak (EW) production of a Z boson, a photon, and two forward jets (Z$\gamma$jj) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. A data set corresponding to an integrated luminosity of 137 fb$^{-1}$, collected by the CMS experiment at the LHC in 2016-2018 is used. The measured fiducial cross section for EW Z$\gamma$jj is $\sigma_{\mathrm{EW}}$ = 5.21 $\pm$ 0.52 (stat) $\pm$ 0.56 (syst) fb = 5.21 $\pm$ 0.76 fb. Single-differential cross sections in photon, leading lepton, and leading jet transverse momenta, and double-differential cross sections in $m_{\mathrm{jj}}$ and $\lvert\Delta\eta_{\mathrm{jj}}\rvert$ are also measured. Exclusion limits on anomalous quartic gauge couplings are derived at 95% confidence level in terms of the effective field theory operators $\mathrm{M}_{0}$ to $\mathrm{M}_{5}$, $\mathrm{M}_{7}$, $\mathrm{T}_{0}$ to $\mathrm{T}_{2}$, and $\mathrm{T}_{5}$ to $\mathrm{T}_{9}$.
The measured inclusive fiducial cross section for the pure electroweak Z$\gamma$jj production. The uncertainty of the observed results includes the stastical uncertianty and the systematic uncertainty, while the uncertainty of the predicted results is the theoretical uncertainty from the MadGraph5_aMC@NLO.
The measured inclusive fiducial cross section for the combined QCD-induced and electroweak Z$\gamma$jj production. The uncertainty of the observed results includes the stastical uncertianty and the systematic uncertainty, while the uncertainty of the predicted results is the theoretical uncertainty from the MadGraph5_aMC@NLO.
The measured single-differential cross sections in photon transverse momenta for the pure electroweak Z$\gamma$jj production. The total uncertainty of the observed results includes the stastical uncertianty and the systematic uncertainty, while the uncertainty of the predicted results is the theoretical uncertainty from the MadGraph5_aMC@NLO. The last bin includes overflow events.
A measurement is presented of the cross section for electroweak production of a Z boson and a photon in association with two jets (Z$\gamma$jj) in proton-proton collisions. The Z boson candidates are selected through their decay into a pair of electrons or muons. The process of interest, electroweak Z$\gamma$jj production, is isolated by selecting events with a large dijet mass and a large pseudorapidity gap between the two jets. The measurement is based on data collected at the CMS experiment at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The observed significance of the signal is 3.9 standard deviations, where a significance of 5.2 standard deviations is expected in the standard model. These results are combined with published results by CMS at $\sqrt{s} =$ 8 TeV, which leads to observed and expected respective significances of 4.7 and 5.5 standard deviations. From the 13 TeV data, a value is obtained for the signal strength of electroweak Z$\gamma$jj production and bounds are given on quartic vector boson interactions in the framework of dimension-eight effective field theory operators.
The measured EWK Zgamma+2j fiducial cross section. The uncertainty is the combined stastical uncertianty and the systematic uncertainty including experimental and theortical sources
The measured combined QCD-induced and EWK Zgamma+2j fiducial cross section. The uncertainty is the combined stastical uncertianty and the systematic uncertainty including experimental and theortical sources
aQGC limits on effective field theory parameters in EWK Zgamma events
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