Electric dipole moment of the top quark in Higgs-boson-exchange models ofCPnonconservation

The leading contribution to the electric and the chromoelectric dipole moments of the top quark is calculated in Higgs-boson-exchange models of CP nonconservation. The dipole moments are typically of the order of ${10}^{\mathrm{-}20}$ e cm and ${10}^{\mathrm{-}20}$ g cm, respectively and arise at one-loop order through neutral-Higgs-boson exchange. Several two-loop contributions are estimated to be smaller by about 2 orders of magnitude for the electric case and about 1 order of magnitude smaller for the chromoelectric case. The ${\mathit{q}}^2$ dependence of the dipole moment form factor is given for possible application to experimental searches.