CP VIOLATION IN TOP-QUARK PAIR PRODUCTION AT A NEXT LINEAR COLLIDER

We provide a detailed, model-independent study for CP-violation effect s due to the T-odd top-quark electric dipole moment (EDM) and weak dip ole moment (WDM) in top-quark pair production via e(+)e(-) and two-pho ton annihilation at a Next e(+)e(-) Linear Collider (NLC). There are t wo methods in detecting CP-violation effects in these processes. One m ethod makes use of measurements of various spin correlations in the fi nal decay products of the produced top-quark pair, while the other is to measure various CP-odd polarization asymmetry effects of the initia l states. In the e(+)e(-) case only the first method can be used and i n the gamma gamma case both methods can be employed. We provide a comp lete classification of angular correlations of the t and t decay produ cts under CP and CP (T) over tilde which greatly faciliate CP tests in the e(+)e(-) mode. Concentrating on the second method with the Compto n backscattered high-energetic laser light off the electron or positro n beam in the two-photon mode, we construct two CP-odd and CP (T) over tilde-even initial polarization configurations and apply them to inve stigating CP-violating effects due to the top-quark EDM. With a typica l set of experimental parameters at the NLC, we compare the 1 sigma se nsitivities to the top-quark EDM and WDM in the e(+)e(-) mode and the two-photon mode. Some model expectation values of the T-odd parameters are compared with the results. [S0556-2821(97)04423-8].