New-Physics Search in gamma gamma --> t tbar

We performed an analysis on possible anomalous top-quark couplings generated by SU(2) x U(1) gauge-invariant dimension-6 effective operators, applying the optimal-observable procedure to the final lepton/b-quark momentum distribution in gamma gamma --> t tbar --> l X/b X. We studied how many such anomalous coupling constants could be determined altogether through these distributions.