e+e−→tt¯Hwith nonstandard Higgs boson couplings

We consider a general effective Lagrangian for couplings of a Higgs boson to the top quark to dimension-six operators including $\mathrm{CP}$ violation effects. Constraints on some of them are derived from the $\overrightarrow{Z}b\overline{b}$ data. We study the process $e^{+}{e}^{-}\to t\overline{t}H$ to probe the nonstandard couplings. We find that at a linear collider with a c.m. energy $\sqrt{s}\sim 0.5-1.5$ TeV and a high luminosity of $10-1000\hspace{0.5em}{\mathrm{fb}}^{-1},$ these non-standard couplings may be sensitively probed.