Measurement of the inclusive WZ production cross section in pp collisions at $ \\sqrt{s}= $ 13.6 TeV

The inclusive WZ production cross section is measured in proton-proton collisions at a centre-of-mass energy of 13.6 TeV, using data collected during 2022 with the CMS detector, corresponding to an integrated luminosity of 34.7 fb$^{-1}$. The measurement uses multileptonic final states and a simultaneous likelihood fit to the number of events in four different lepton flavour categories: eee, ee$\\mu$, $\\mu\\mu $e, and $\\mu\\mu\\mu$. The selection is optimized to minimize the number of background events, and relies on an efficient prompt lepton discrimination strategy. The WZ production cross section is measured in a phase space defined within a 30 GeV window around the Z boson mass, as $\\sigma_{\\text{total}}$(pp$\\to$WZ) = 55.2$\\pm$1.2 (stat) $\\pm$1.2 (syst) $\\pm$0.8 (lumi) $\\pm$0.1 (theo) pb. In addition, the cross section is measured in a fiducial phase space closer to the detector-level requirements. All the measurements presented in this paper are in agreement with standard model predictions.