Topics in Supersymmetry

Radiative corrections to the masses of the CP -even Higgs bosons are calculated using the effective potential approximation. Bounds for the masses of the heavy and light Higgs are obtained. Corrections to the decay rate Gamma(H to ZZ) due to a third generation of quarks and squarks are also computed using a diagrammatic approach. The tree level rate is suppressed for large M_{H}. We find that the corrections grow as M_{H} gets large and can significantly increase the rate. A string-inspired supergravity model is analyzed at one loop. The vacuum degeneracy is lifted and the parameters of the low energy theory are determined. ftn*This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Division of High Energy Physics of the U.S. Department of Energy under contract DE-AC03 -76SF00098 and in part by the National Science Foundation under grant PHY-90-21139.