Measurement of Wγ and Zγ production in pp collisions at √s = 7 TeV

A measurement of Wγ and Zγ production in proton–proton collisions at √s = 7 TeV is presented. Results are based on a data sample recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 36 pb^(−1). The electron and muon decay channels of the W and Z are used. The total cross sections are measured for photon transverse energy E_t^y > 10 GeV and spatial separation from charged leptons in the plane of pseudorapidityand azimuthal angle ΔR(l,γ)>0.7, and with an additional dilepton invariant massrequirement of M_(ll)>50 GeV for the Zγ process. The following cross section times branching fractionvalues are found: σ(pp → Wy + X) x B(W → lv)= 56.3 ± 5.0 (syst.) ± 2.3 (lumi.) pb and σ(pp → Zy + X) x B(Z → ll) = 9.4 ± 1.0 (stat.)± 0.6(syst.) ± 0.4(lumi.)pb. These measurements are in agreement with standard model predictions. The first limits on anomalous WWγ, ZZγ, and Zγγ trilinear gauge couplings at √s = 7 TeV are set.