Search for Higgs bosons using the L3 detector at LEP

This thesis is devoted to the search for Higgs bosons predicted by various theoretical models. By the introduction of these particles into the theory, the masses of bosons and fermions can be explained. The search is performed in experimentally related channels, which are characterised by charged leptons in the final state. The analysis uses data taken during the years 1996-1998 with the L3 detector at the large electron positron collider LEP. The observed candidates are consistent with the expectation from standard model background processes. Evidence for Higgs boson production could not be found. New mass limits were determined superseding previous mass limits established by L3 and other experiments. In the search for the Higgs boson of the standard model the channels hZ #-># b anti bl"+l"- (l = e,#mu#,#tau#) and hZ #-># #tau#"+#tau#"-q anti q were analysed at centre-of-mass energies between 183 and 189 GeV. A lower mass limit of m_h > 87.5 GeV is derived at the 95% confidence level. (orig.)106 refs.Available from TIB Hannover: RR 8919(2000-009) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman