Top quark electric dipole and Zγγ couplings at a photon collider

Effect of the top quark electric dipole coupling and the Zγγ coupling is studied in the pair production of top quark at a photon collider using CP-violating asymmetries. Our results show that with a photon collider of geometrical luminosity of 20 fb−1 it is possible to put limits of the order of 0.1 on the Zγγ coupling and about 2.5×10−17e cm on the top quark electric dipole coupling using these asymmetries.