Abstrakt
A measurement of W gamma and Z gamma production in proton-proton collisions at root 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)(gamma) } 10 GeV and spatial separation from charged leptons in the plane of pseudorapidity and azimuthal angle Delta R(l.gamma) } 0.7, and with an additional dilepton invariant mass requirement of M(ll) } 50 GeV for the Z gamma process.
The following cross section times branching fraction values are found: sigma(pp -} W gamma + X) x B(W -} lv) = 56.3 +/- 5.0(stat.) +/- 5.0(syst.) +/- 2.3(lumi.) pb and sigma(pp -} Z gamma + 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 WW gamma, ZZ gamma, and Z gamma gamma trilinear gauge couplings at root s = 7 TeV are set.