Three-Body Decays of SUSY Particles

We analyze the decays of charginos, neutralinos, gluinos and the first/second generation squarks in the Minimal Supersymmetric extension of the Standard Model, focusing on the three-body decays in scenarios where the ratio $\tan \beta$ of vacuum expectation values of the two Higgs doublet fields is large. We show that the three-body decays of the next-to-lightest neutralinos (lightest charginos) into $b\bar{b},\tau^+\tau^-$ ($\tau \nu$) final states, where third generation sfermion and Higgs boson exchange diagrams play an important role, are dominant. Furthermore, we show that decays of gluinos into $b\bar{b}$ final states and squark decays into lighter sbottoms through gluino exchange can also have sizeable branching fractions, especially in scenarios where the soft SUSY breaking gaugino mass parameters are not unified at the GUT scale.