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RESEARCH PRODUCT

Precision measurements of electroweak gauge boson parameters at LEP

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Abstract Over ten years after the start-up of LEP and four years after the completion of the energy scans around the Z resonance the analyses of the Z parameters by the four experiments Aleph, Delphi and L3 are final and the Opal results are very close to final. The analyses of the polarisation of τ leptons and measurements of the production rates and forward-backward asymmetries in the heavy flavour sector are approaching their finalisation. Recent data taking nearly doubled the statistics of W± pair events available at Lep and lead to significantly improved preliminary measurements of the W± pair production cross section, the W mass and branching fractions as well as improved limits on non-standard couplings at the triple gauge boson vertices. Altogether, in combination with measurements of the weak mixing angle at the SLC and the top quark mass at the Tevatron, these results provide stringent test of the Standard Model of the electroweak interaction and constrain its last missing parameter, the mass of the Higgs boson.