A search for neutral Higgs bosons in the MSSM and models with two scalar field doublets

A search is described for the neutral Higgs bosons and predicted by models with two scalar field doublets and, in particular, the Minimal Supersymmetric Standard Model (MSSM). The search in the and production channels is based on data corresponding to an integrated luminosity of 25 pb from collisions at centre-of-mass energies between 130 and 172 GeV collected with the OPAL detector at LEP. The observation of a number of candidates consistent with Standard Model background expectations is used in combination with earlier results from data collected at the resonance to set limits on and in general models with two scalar field doublets and in the MSSM. For example, in the MSSM, for , minimal and maximal scalar top quark mixing and soft SUSY-breaking masses of 1 TeV, the 95% confidence level limits GeV and GeV are obtained. For the first time, the MSSM parameter space is explored in a detailed scan. Received: 20 February 1998 / Published online: 13 July 1998