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The authors present a measurement of the {bar p}p {yields} W{gamma} + X {yields} e{nu}{gamma} + X production cross section using data form the Collider Detector at Fermilab. The p{bar p} collisions were provided by the Tevatron Collider at a center of mass energy of 1.96 TeV. Electroweak theory includes the trilinear vector boson coupling, WW{gamma}, which contributes to the e{nu}{gamma} final state. The electron decay channel of the W provides a clean sample to study the production of diboson pairs. The measurement of the production cross section tests the structure of the non-Abelian character of Electroweak theory.
The production cross section and the kinematic properties of the decay products of the W[gamma] in the W [yields] [mu][nu] decay channel from p[bar p] collisions at [radical]s = 1.96 TeV are presented. The measurement use the high p[sub T] muon data from the upgraded Collider Detector at Fermilab (CDF). The data were collected between March 2002 and September 2003. The total integrated luminosities are 192 pb[sup -1] with the muon detector which covers the pseudorapidity region of [eta] [le] 0.6 and 175 pb[sup -1] with the muon detector covering the region 0.6 [le] [eta] [le] 1.0. In the Standard Model the [mu][nu][gamma] final states occur due to W[gamma] [yields] [mu][nu][gamma] production and via muon Bremsstrahlung, W [yields] [mu][nu] [yields] [mu][nu][gamma]. W bosons are selected in their muon decay mode. Additionally, photons with transverse energy above 7 GeV, pseudorapidity in the central region ([eta] 1.1) and muon-photon angular separation [Delta]R([mu], [gamma]) 0.7 are selected. They observe a total of 128 W[gamma] candidates, whereas the Standard Model expectation is 142.4 [+-] 9.5 events. The W[gamma] production cross section is found to be [sigma](p[bar p] [yields] [mu][nu][gamma]) = 16.3 [+-] 2.3(stat.) [+-] 1.8(syst.) [+-] 1.2(lum.) [pb]. The theoretical prediction for this cross section is [sigma](p[bar p] [yields] l[nu][gamma]) = 19.3 [+-] 1.4(th.)[pb]. The Standard Model predictions for several kinematic + variables are compared with data for E[sub T][gamma]> 7 GeV and [Delta]R([mu], [gamma])> 0.7. The measured cross section and the photon and W boson production kinematics are found to agree with the Standard Model predictions.
A measurement of W-gamma and Z-gamma production in proton-proton collisions at sqrt(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 inverse picobarns. The electron and muon decay channels of the W and Z are used. The total cross sections are measured for photon transverse energy>10 GeV and spatial separation from charged leptons in the plane of pseudorapidity and azimuthal angle>0.7, and with an additional dilepton invariant mass requirement of> 50 GeV for the Z-gamma process. The following cross section times branching fraction values are found: sigma(pp to W-gamma+X) B(W to lepton neutrino) = 56.3 +/- 5.0 (stat.) +/- 5.0 (syst.) +/- 2.3 (lumi.) pb and sigma(pp to Z-gamma+X) B}(Z to lepton lepton) = 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 sqrt(s) = 7 TeV are set.
"From 2015 to 2018, the Large Hadron Collider (LHC) collided protons at an unprecedented centre of mass energy of √s = 13 TeV. The ATLAS detector recorded an integrated luminosity of 139 fb−1 of these collisions hence offering an unprecedented opportunity to test the Standard Model (SM) of particle physics by measuring predicted but yet unobserved rare processes. The tri-boson W[gamma][gamma] production is one of these unobserved processes. Its sensitivity to the electroweak trilinear and quartic gauge couplings make it a great probe of new physics phenomena as Beyond Standard Model processes could affectthe effective strength of these couplings. This thesis presents the study of the W[gamma][gamma] process. Backgrounds are estimated from a combination of Monte Carlo (MC) simulations and data-driven techniques. The dominant source of background to the search for W[gamma][gamma] production are jets being misidentified as photons. The advanced data-driven technique used to estimate this background is presented in details. Finally thorough examination of the systematic uncertainties affecting the measurement of the W[gamma][gamma] production cross-section are presented. Taking into account all statistical and systematic uncertainties, the expected statistical significance of the measurement is of 5.1 [delta] for the differential measurement and 7.8 [delta] for the total cross-section"--