Studying Possible Anomalous Top-Quark Couplings at Photon Colliders
  Search for new-physics through possible anomalous t tbar gamma, tbW and gamma gamma H couplings which are generated by SU(2) X U(1) gauge-invariant dimension-6 effective operators is discussed, using energy and angular distributions of final charged-lepton/ b-quark in gamma gamma -> t tbar -> l X / bX for various beam polarizations. Optimal beam polarizations that minimize uncertainty in determination of those non-standard couplings are found performing an optimal-observable analysis. 
Bohdan Grzadkowski (Warsaw U.), Zenro Hioki (U. Tokushima), Kazumasa   Ohkuma (Fukui U. Tech.), Jose Wudka (UC, Riverside)