Renormalization Group Analysis of Supersymmetric Particle Interactions

We reexamine the renormalization group equations (RGEs) for the dimensionless and dimensionful parameters of the Minimal Supersymmetric Standard Model (MSSM), incorporating 1-loop thresholds. The inclusion of these thresholds necessarily results in splitting between dimen-sionless couplings which are equal at the tree level. Assuming that the SUSY-breaking mechanism does not introduce new intergenerationalcouplings, we present the most general form for high-scale, soft-SUSY-breaking (SSB) parameters. With this as our boundary condition, we consider illustrative examples of numerical solutions to the RGEs. In a supersymmetric grand unified theory with the scale of SUSY scalars split from that of gauginos and higgsinos, we find that the gaugino mass unification relation may be violated to the order of 10%. Further, we consider the rate for the flavor violating decay of the lightest stop to charm plus neutralino. We find that using the complete RGE solution as opposed to the commonly used 'single-step' integration of the RGEs can qualitatively change the picture of event-topologies from top-squark pair production, or from gluino production if gluino to stop plus top is the dominant gluino decay mode.