CMS-SMP-14-018

CMS-SMP-14-018
Evidence for the electroweak $Z\gamma$ production in association with two jets and a search for anomalous quartic gauge couplings in pp collisions at $\sqrt{s} =$ 8 TeV
CMS Collaboration
September 2015

Abstract: Evidence for electroweak associated production of a Z boson, a photon and two jets, where the Z boson decays into electron or muon pairs, is presented. The measurement is based on a sample of proton-proton collisions collected by the CMS detector at a center of mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb ${-1}$ . Limits on anomalous quartic gauge couplings are set with a binned profile likelihood method based on the $M_{Z\gamma}$ distribution.
Links: CDS record (PDF) ; CADI line (restricted) ; Figures are also available from the CDS record. These preliminary results are superseded in this paper, PLB 770 (2017) 380. The superseded preliminary plots can be found here.

Figures
png ; pdf	Figure 1: Representative diagrams for EWK $\ell \ell \gamma jj$ Productions at the LHC: (a) Bremsstrahlung, (b) Multiperipheral, (c) VBF with TGC, and (d) VBS with QGC processes.
png ; pdf	Figure 2-a: The $M_{jj}$ distributions measured in (a) muon and (b) electron channels. The data (solid symbols with error bars representing the statistical uncertainties) are compared to background estimate based on data as described in the text convoluted with MC predictions for the signal contribution. The shadowed bands represent the full uncertainty on predictions as described in Section 6. The last bin is overflow bin that contains the events above 1200 GeV.
png ; pdf	Figure 2-b: The $M_{jj}$ distributions measured in (a) muon and (b) electron channels. The data (solid symbols with error bars representing the statistical uncertainties) are compared to background estimate based on data as described in the text convoluted with MC predictions for the signal contribution. The shadowed bands represent the full uncertainty on predictions as described in Section 6. The last bin is overflow bin that contains the events above 1200 GeV.
png ; pdf	Figure 3: The upper limit on Standard Model EWK Z $\gamma$ +two jets cross section, for muon channel and electron channel using $CL_{s}$ construction
png ; pdf	Figure 4: The distribution of events pass the final cut criteria for searching aQGCs. The last bin has been extended to include overflow evens. Errors in the plot are shown with statistical uncertainties for background and data (in bars), and theoretical uncertainties for aQGCs (in bands).
png ; pdf	Figure 5-a: Comparison of the limits on the dimension 8 AQGC parameters obtained from this study, together with results from WV $\gamma$ production, same sign WW production, exclusive $\gamma \gamma \to { {\mathrm {W}} {\mathrm {W}}}$ production at CMS and W $\gamma \gamma$ production at ATLAS.
png ; pdf	Figure 5-b: Comparison of the limits on the dimension 8 AQGC parameters obtained from this study, together with results from WV $\gamma$ production, same sign WW production, exclusive $\gamma \gamma \to { {\mathrm {W}} {\mathrm {W}}}$ production at CMS and W $\gamma \gamma$ production at ATLAS.

Tables
png ; pdf	Table 1: Parameterized by $Z\gamma$ mass, 95% CL shape-based exclusion limits listed for combined channels of each aQGC parameter, no form factor is applied.

Compact Muon Solenoid
LHC, CERN