The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by the Minimal Supersymmetric Standard Model (MSSM). The data of the four collaborations are statistically combined and examined for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number of "benchmark" models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large exclusions in the MSSM parameter space. Absolute limits are set on the parameter tan β and, in some scenarios, on the masses of neutral Higgs bosons.

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The spectral functions of the vector current and the axial-vector current have been measured in hadronic τ decays using the OPAL detector at LEP. Within the framework of the Operator Product Expansion a simultaneous determination of the strong coupling constant α s , the non-perturbative operators of dimension 6 and 8 and of the gluon condensate has been performed. Different perturbative descriptions have been compared to the data. The Contour Improved Fixed Order Perturbation Theory gives α s (m 2 τ ) = 0.348±0.009 exp ±0.019 theo at the τ -mass scale and α s (m 2 Z ) = 0.1219±0.0010 exp ±0.0017 theo at the Z 0 -mass scale. The values obtained for α s (m 2 Z ) using Fixed Order Perturbation Theory or Renormalon Chain Resummation are 2.3 % and 4.1 % smaller, respectively. The 'running' of the strong coupling between s 0 ≃ 1.3 GeV 2 and s 0 = m 2 τ has been tested from direct fits to the integrated differential hadronic decay rate R τ (s 0 ). A test of the saturation of QCD sum rules at the τ -mass scale has been performed.

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