In this thesis we study two important phenomenological issues in the context of supersymmetric gauge theories. In the Minimal Supersymmetric Standard Model (MSSM) we analyze properties of the neutral Higgs boson decays into two neutralinos, taking into account the effect of new quantum corrections. In the second part of our work we study in detail the Proton decay in the Minimal Supersymmetric SU(5) Theory. We compute one-loop corrections to the neutralino couplings to the Higgs bosons, taking into account contributions with fermions and sfermions inside the loop. Our analytical results are valid for arbitrary momenta and general sfermion mixings. For the neutralino couplings to Higgs bosons, we find in all cases corrections of up to a factor of two for reasonable values of the input parameters. The contribution of Bino--like lightest supersymmetric particles to the invisible decay width of the lightest MSSM Higgs boson might be measurable at future high--energy and high--luminosity e^+ e^- colliders, when the new quantum corrections are present. The masses(M_T) of the heavy triplets T and \bar T responsible for d=5 proton decay are computed, when we allow for arbitrary trilinear coupling of the heavy fields in Sigma and use higher dimensional terms as a possible source of their masses. In this case M_T may go up naturally by a factor of thirty, which would increase the proton lifetime by a factor of 10^3. The relation between fermion and/or sfermion masses, and proton decay is studied in detail. We find the conditions needed to suppress the d=5 contributions to the decay of the proton, in the context of the Minimal Supersymmetric SU(5) model. We point out that the Minimal Supersymmetric Grand Unified Theory SU(5) is not ruled out as claimed before.     «

In this thesis we study two important phenomenological issues in the context of supersymmetric gauge theories. In the Minimal Supersymmetric Standard Model (MSSM) we analyze properties of the neutral Higgs boson decays into two neutralinos, taking into account the effect of new quantum corrections. In the second part of our work we study in detail the Proton decay in the Minimal Supersymmetric SU(5) Theory. We compute one-loop corrections to the neutralino couplings to the Higgs bosons, taking i...     »

Diese Arbeit behandelt zwei phänomenologische Aspekte supersymmetrischer Feldtheorien. Im Rahmen des minimalen supersymmetrischen Standardmodells (MSSM) werden wichtige Quantenkorrekturen zum Zerfall neutraler Higgs-Bosonen in Gauginoartige Neutralinos berechnet. Diese Korrekturen können das Verzweigungsverhältnis um einen Faktor zwei verändern. Weiterhin wird der Protonzerfall im Rahmen des minimalen supersymmetrischen SU(5) Modells analysiert. Es wird gezeigt, dass dieses Modell mit allen Daten kompatibel gemacht werden kann, wenn Flavor-Mischung im Sfermion- und Fermion-Sektor unterschiedlich ist, oder wenn man nicht-renormierbare Terme in den Yukawa-Kopplungen oder in den Selbstkopplungen der superschweren Higgs-Superfelder zuläßt.     «

Diese Arbeit behandelt zwei phänomenologische Aspekte supersymmetrischer Feldtheorien. Im Rahmen des minimalen supersymmetrischen Standardmodells (MSSM) werden wichtige Quantenkorrekturen zum Zerfall neutraler Higgs-Bosonen in Gauginoartige Neutralinos berechnet. Diese Korrekturen können das Verzweigungsverhältnis um einen Faktor zwei verändern. Weiterhin wird der Protonzerfall im Rahmen des minimalen supersymmetrischen SU(5) Modells analysiert. Es wird gezeigt, dass dieses Modell mit allen Date...     »