Optimal Beam Polarizations for New-Physics Search through gamma gamma ->   t tbar -> lX/bX
  We perform an optimal-observable analysis of the final charged-lepton/b-quark momentum distributions in gamma+gamma -> t+tbar -> lX/bX for various beam polarizations in order to study possible anomalous t-tbar-gamma, tbW and gamma-gamma-H couplings, which could be generated by SU(2)xU(1) gauge-invariant dimension-6 effective operators. We find optimal beam polarizations that will minimize the uncertainty in determination of those non-standard couplings. We also compare e+ebar and gamma+gamma colliders from the viewpoint of the anomalous-top-quark-coupling determination. 
Bohdan Grzadkowski (Warsaw U.), Zenro Hioki (U. Tokushima), Kazumasa   Ohkuma (Fukui U. Tech.), Jose Wudka (UC Riverside)