Non - Minimal Supersymmetric Higgs Bosons at LEP 2

We discuss the discovery reach of LEP2 for the Higgs sector of a general extension of the MSSM including a single gauge singlet field. This change introduces a new quartic Higgs boson self-coupling which can increase the masses of the CP-even states, and also allows mixing between singlet and non-singlet states which can reduce the couplings of the mass eigenstates to the Z. The lightest CP-even Higgs boson is bounded by a parameter Λ which takes a maximum value Λmax ≈ 136− 146 GeV for top mass 150 − 195 GeV. We generalise the discussion of the bound to include the entire CP-even spectrum and show how experiment may exclude values of Λ smaller than some Λmin. CP-even Higgs boson searches at LEP2 will be able to exclude Λmin ≈ 81 − 105 GeV, depending on the machine parameters. We also present exclusion plots in the mA − tanβ plane, based on an analysis of CP-even, CP-odd and charged Higgs production processes at LEP2.