Neutral Higgs Boson Production and CP Violation at LC

Conventional wisdom is that the standard model (SM) is not the final theory but just an effective theory of a fundamental structure. The two Higgs-doublet (2HD) model is one of the simplest extension of the SM, which consist of two SU(2) scalar doublets. A discrete symmetry is often introduced to avoid a dangerous flavour-changing neutral currents (FCNC) in the 2HD model, which forbids the CP violating terms in the Higgs potential. If we abandon the discrete symmetry, complex Higgs self-couplings exist in general, and consequently the explicit and spontaneous CP violation is allowed in the Higgs sector. In that case, Higgs-mediated FCNC are present at tree level and we must consider a way to suppress the FCNC, e.g. to assume an approximate flavour symmetry. Its phenomenological implicatiions have been widely studied . In this work, we focus on the Higgs-gauge sector in the general 2HD model with CP violation and study the neutral Higgs boson production at the ee Linear Colliders (LC).