CMS-PAS-SMP-19-008

CMS-PAS-SMP-19-008
Observation of the electroweak production of W $\gamma$ in association with two jets in proton-proton collisions at $\sqrt{s}=$ 13 TeV
CMS Collaboration
May 2020

Abstract: A measurement of the electroweak (EW) production of a W boson and a photon in association with two jets in proton-proton collisions, where the W boson decays leptonically, is presented. Events are selected by requiring one identified electron or muon, missing transverse momentum, one photon, and two jets with a large dijet mass and a large rapidity separation. The measurement is based on data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb $^{-1}$ . The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results based on 8 TeV data, the observed (expected) significance is 5.3 (4.8) standard deviations. This constitutes the first observation of EW W $\gamma$ production in pp collisions. The cross section measured in the fiducial region is 20.4 $\pm$ 4.5 fb and the total cross section for EW + QCD W $\gamma$ production in association with 2 jets in the same fiducial region is measured to be 108 $\pm$ 16 fb. All measurements are in good agreement with recent theory predictions. We set the most stringent limits to date on the anomalous quartic gauge coupling parameters $F_\mathrm{M,2-5}$ and $F_\mathrm{T,6-7}$ .
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; These preliminary results are superseded in this paper, PLB 811 (2020) 135988. The superseded preliminary plots can be found here.

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