Anomalous $ZZ\gamma$ And $Z\gamma\gamma$ Couplings At LEP2
C Palomares · CERN Document Server (European Organization for Nuclear Research) · 1998
We have studied the existence of anomalous $ZZ\gamma$ and $Z\gamma\gamma$ couplings using the L3 detector at LEP. The analysis is based on the study of the process $e^+e^- \to Z\gamma$ at center-of-mass energies between 161 GeV and 183 GeV. The observed rates of events with $E\gamma\approx \frac{\sqrt{s}}{2}$ $(1-M^2_Z/s)$ and the characteristic distributions are in agreement with the Standard Model expectations. This is used to set limits on the eight possible anomalous couplings and to exclude new physics scales in the range 250-700 GeV , depending on the type of coupling.