Special aspects of weak decays with regard to the detection of new hadrons and leptons

Phenomenological aspects of the weak interaction were investigated with regard to criteria for the detection of new particles of higher mass (B, L0). Predictions for the weak decays of heavy hadrons with new quantum numbers (e.g. Bottom) require an understanding of the different semileptonic branching ratios (about 1/100) of K and D mesons. In chapter 2, the non-leptonic decays of strange and charmed mesons were investigated in order to explain this discrepancy, using two-dimensional QCD as a model for the calculation of the influence of strong interaction on the weak decays. The semileptonic decays of bottom mesons led to di-, tetra- and tetralepton events in e+e- annihilation experiments. Chapter 3 points out that the bottom particles can be detected by measuring these multilepton rates. As the model-independent analysis of the author shows, the semileptonic branching ratio, the relative strength of the bc and bu couplings, and the B0-B-0 mixing can thus be directly determined. It was found already for the case of the heavy lepton tau that a direct extrapolation of the weak interaction to the purely leptonic decays of heavy leptons is possible. In chapter 4, the production and decay of a heavy neutral muon L0 in UPSILONμ(μ+-) scattering are investigated. (orig./HSI)