CP-violating Z gamma gamma and top-quark electric dipole couplings in gamma gamma -> tt

An effective anomalous CP-violating Z gamma gamma coupling can give rise to observable CP-odd effects in gamma gamma --> t (t) over bar. We study cert ain asymmetries in the decay lepton distributions in gamma gamma-->t (t) ov er bar arising from top decay in the presence of a CP-violating Z gamma gam ma coupling as well as a top-quark electric dipole coupling. We find that a photon linear collider with geometric luminosity of 20 fb(-1) can put limi ts of the order of 0.1 on the imaginary part of the CP-violating anomalous Z gamma gamma coupling using these asymmetries. (C) 1999 Published by Elsev ier Science B.V. All rights reserved.