Searches for Higgs bosons beyond the standard model at LEP

Searches for various types of Higgs bosons in models beyond the Standard Model (SM) are reported. They are based on data taken by the four LEP experiments ALEPH, DELPHI, L3 and OPAL at centre-of-mass energies up to 189 GeV. The searches comprise neutral and charged Higgs bosons in models with two Higgs doublers, in particular the Minimal Supersymmetric Standard Model (MSSM). Non standard decay modes of Higgs bosons like decays into photons and invisible decays are also covered. None of the searches revealed a significant excess over the expectation from SM background processes. Therefore new limits on Higgs boson masses and other model parameters are reported. (10 refs)