Two Higgs Doublets Models and CP Violating Higgs Exchange in e+ e- -> t bar-t Z

Appreciable CP Asymmetries (~ 10%) can arise in the reaction e+ e- -> t bar-t Z already at TREE-LEVEL in models with two Higgs doublets. For a neutral Higgs particle, h, with a mass in the range 50 GeV < m_h < 400 GeV, it may be possible to detect a 2-3 sigma CP-odd effect in e+ e- -> t bar-t Z in ~ 1-2 years of running of a future high energy e+e- collider with c.m. energies of ~ 1-2 TeV and an integrated luminosity of 200-500 inverse fb.