K-L-]PHI(0)NU(NU)OVER-BAR IN EXTENDED HIGGS MODELS

The decay K-L --> pi(0)<nu(nu)over bar> is an excellent probe of the n ature of CP violation. It is almost entirely CP violating, and hadroni c uncertainties are negligible. Experiments which hope to detect the d ecay are currently being planned. We calculate the decay rate in sever al extensions of the standard model Higgs sector, including the Liu-Wo lfenstein two-doubler model of spontaneous CP violation and the Weinbe rg three-doublet model. in a model with an extra doublet, with CP viol ation arising from the CKM sector, the rate can increase by up to 50%. However, in models in which the CP violation arises either entirely o r predominantly from the Higgs sector. we find that the decay rate is much smaller than that of the standard model, unless parameters of the model are fine-tuned.