Anomalous quartic $ZZ\gamma\gamma$ couplings at the CLIC
  We study the sensitivity to anomalous quartic $ZZ\gamma\gamma$ couplings through the processes $e^{+}e^{-}\rightarrow Z\, Z\, \gamma$, $e^{+}e^{-} \rightarrow e^{+}\gamma^{*} e^{-} \rightarrow e^{+} Z\, Z\, e^{-}$ and $e^{+}e^{-} \rightarrow e^{+}\gamma^{*} \gamma^{*} e^{-} \rightarrow e^{+}\, Z\, Z\, e^{-}$ at the CLIC. We find $95\%$ confidence level bounds on these coupling parameters defining by the dimension-six operators. The best bounds on the anomalous $ZZ\gamma\gamma$ couplings among the three processes are obtained from $e^{+}e^{-}\rightarrow Z\, Z\, \gamma$ at a center of mass energy of $3$ TeV and an integrated luminosity of $590$ fb$^{-1}$. We show that the best bounds obtained on both the anomalous coupling parameters are of the order of $10^{-8}$ GeV$^{-2}$, significantly improving the current bounds. 
M. K\"oksal
hep-ph