Measurement of muon pair production around the Z-resonance using the L3 detector at LEP

The Z and W± bosons, both detected at CERN in 1983, are among the most important particles in the standard model of electro-weak interactions. Together with the massles γ, these heavy bosons are the carriers of the so-called electro-weak force. The LEP (Large Electron Positron) collider provides the opportunity of a precise measurement of the properties of the Z-boson. Its mass MZ and width ΓZ are key-parameters in the standard model. In spite of the relatively small partial width Γμ for Z -> μ+μ-, the reaction e+e->μ+μ-(γ) is the cleanest channel to test the standard model. The measurements of the lineshape and forward-backward asymmetry of this reaction belong to the best methods to determine gV and gA, the neutral current vector and axial vector coupling constants. Accurate measurements of MZ, ΓZ, Γμ, gV and gA provide a stringent test of consistencies and predictions of the standard model. The measurements presented here are performed with the L3 detector, one of the four detectors at the LEP-ring. In this thesis, first a number of aspects of the standard model are discussed. This is followed by a description of the L3 detector, in particular the muon detector. After that the measurements are presented. Finally, the measured lineshape and asymmetry are interpreted in terms of standard model variables, and compared to standard model predictions. (author). 62 refs., 50 figs., 22 tabs