CMS-PAS-SMP-24-002

CMS-PAS-SMP-24-002
Measurement of the Z$ \gamma $ production in proton-proton collisions at $ \sqrt{s}= $ 13.6 TeV
CMS Collaboration
29 March 2025

Abstract: A measurement of the $ Z\gamma $ production cross section in proton-proton collisions at a center-of-mass energy of 13.6 TeV using the leptonic final states is presented. A data set corresponding to an integrated luminosity of 34.8 fb$ ^{-1} $, collected by the CMS experiment at the LHC in 2022 is used. Events with an oppositely charged pair of muons or electrons together with an isolated photon are selected. The measured fiducial cross section for the combined muon and electron channels is 1.896 $ \pm $ 0.006 (th) $\pm$ 0.054 (syst) $\pm$ 0.033 (stat) pb.
Links: CDS record (PDF) ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Leading-order Feynman diagrams for $ \mathrm{Z}\gamma $ production in pp collisions. Left: initial-state radiation. Center: final-state radiation. Right: diagram involving anomalous gauge couplings that are forbidden in the SM at tree level.
png pdf	Figure 2: Post-fit distribution of $ m_{\ell\ell\gamma} $ in the muon channel (left) and electron channel (right).The gray bands represent the total uncertainty, and the lower panels show the data/MC ratio.
png pdf	Figure 2-a: Post-fit distribution of $ m_{\ell\ell\gamma} $ in the muon channel (left) and electron channel (right).The gray bands represent the total uncertainty, and the lower panels show the data/MC ratio.
png pdf	Figure 2-b: Post-fit distribution of $ m_{\ell\ell\gamma} $ in the muon channel (left) and electron channel (right).The gray bands represent the total uncertainty, and the lower panels show the data/MC ratio.

Tables
png pdf	Table 1: Fiducial cross sections for predicted and observed results in each channel. The quoted uncertainties include theoretical, systematic, and statistical components.

Summary

In summary, a measurement of the $ Z\gamma $ production using leptonic final states in proton-proton collisions at a center-of-mass energy of 13.6 TeV is presented. A data set corresponding to an integrated luminosity of 34.8 fb$ ^{-1} $, collected by the CMS experiment at the LHC during 2022 is used. Events with a pair of oppositely charged muons or electrons together with an isolated photon are selected. The measured (predicted) fiducial cross section for the combined muon channel and electron channels is 1.896 $ \pm $ 0.006 (th) $\pm$ 0.054 (syst) $\pm$ 0.033 (stat) (1.922 $ \pm $ 0.006 (th) $\pm$ 0.056 (syst) $\pm$ 0.033 (stat)) pb.

References
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