Measurement of the e+e- -> W+W-gamma Cross-section and Limits on Anomalous Quartic Gauge Couplings with DELPHI
The DELPHI Collaboration, J. Abdallah
TL;DR
This work measures the cross-section for e^+e^- → W^+W^-γ at LEP2 with the DELPHI detector across √s = 189–209 GeV using ~600 pb^-1 of data, focusing on hard, central, isolated photons to probe genuine quartic gauge couplings. Photon energy spectra are analyzed to constrain non-SM quartic couplings in the $W^+W^-Z^0γ$ and $W^+W^-γγ$ sectors, modeled with EEWWG and compared to SM predictions from WPHACT/YFSWW. The measured cross-sections are consistent with the SM within uncertainties, and the study sets 95% confidence limits on $a_c/\Lambda^2$, $a_0/\Lambda^2$, $\tilde{a}_0/\Lambda^2$, $a_n/\Lambda^2$, and $\tilde{a}_n/\Lambda^2$, thereby constraining genuine QGCs at LEP2 energies. These results complement other LEP analyses and demonstrate the sensitivity of radiative W-pair production to new physics in a model-independent QGC framework.
Abstract
W+W-gamma production at LEP2 is studied using data collected with the DELPHI detector at centre-of-mass energies between 189 GeV and 209 GeV, corresponding to an integrated luminosity of about 600 pb^-1. Cross-sections are measured for the production of W+W- with a hard, central and isolated photon in the final state, and are found to be compatible with the Standard Model prediction. The photon energy spectra are used to derive limits on anomalous contributions to the W+W-Z0gamma and W+W-gammagamma vertices.