Probe of new physics in top-quark pair production at e-e+ colliders.

We describe how to probe new physics through examination of the form factors describing the $Z\ensuremath{-}t\ensuremath{-}\overline{t}$ couplings via the scattering process ${e}^{\ensuremath{-}}{e}^{+}\ensuremath{\rightarrow}t\overline{t}$. We focus on experimental methods on how the top-quark momentum can be determined and show how this can be applied to select polarized samples of $t\overline{t}$ pairs through the angular correlations in the final state leptons. We also study the dependence on the energy and luminosity of an ${e}^{\ensuremath{-}}{e}^{+}$ collider to probe a $\mathrm{CP}$-violating asymmetry at the ${10}^{\ensuremath{-}2}$ level.