CONSTRAINING THE 2 HIGGS DOUBLET MODEL BY PRESENT AND FUTURE (G-2)(MU) DATA

Constraints on the general two Higgs doublet model (''model II'') are obtained from the existing (g-2)(mu) data including limits on Higgs bo son masses from CERN LEP I data. We consider two scenarios: with a lig ht scalar h and with a light pseudoscalar A, assuming M-h+M-A greater than or equal to M-Z (the charged Higgs boson contribution is also inc luded). We evaluate separately the 95% C.L. bands for positive and for negative contributions, relevant for a light scalar and a light pseud oscalar scenario, respectively. It is found that already the present ( g-2)(mu) data improve limits obtained recently by the ALEPH Collaborat ion on tan beta for the mass of the pseudoscalar below less than or si milar to 2 GeV. The improvement in the accuracy by a factor of 20 in t he forthcoming E821 experiment may lead to more stringent limits than provided by the ALEPH group, up to M-A similar to 30 GeV if the mass d ifference between h and A is similar to M-Z. Similar results should ho ld for a light scalar scenario as well.