Probing anomalous top-quark couplings induced by dim.6 operators at photon colliders Original Research Article

Possible anomalous top-quark couplings induced by SU(2)×U(1) gauge-invariant dimension-6 effective operators were studied in the process of tt̄ productions and decays at polarized γγ colliders. Two CP-violating asymmetries, a linear-polarization asymmetry and a circular-polarization asymmetry, were computed including both non-standard tt̄γ and γγH couplings. An optimal-observable analysis for the process γγ→tt̄→l±⋯ was performed in order to estimate the precision for determination of all relevant non-standard couplings, including the anomalous tbW coupling.