Pursuing supersymmetry in Z0 decays

We use recent LEP and SLC data on Z0 decays and p ̄p collider limits on W±, Z0 and gluino production to constrain the parameters of the chargino-neutralino sector in the minimal supersymmetric extension of the standard model. We show that unsuccessful chargino and gluino scarches, the p ̄p collider ratio R ≡ σWe/σZe, and measurements of total Z0 width, peak hadronic cross section and invisible Z0 width provide important constraints. The most stringent present bounds on invisible Z0 decays assume the standard model for hadronic final states, and are therefore not directly applicable to supersymmetric models, which may have additional visible Z0 decay modes. Possible signatures for supersymmetry in future Z0 measurements include excesses in the total Z0 width or in the invisible Z0 width, but the most promising signal would be an observable cross section for "zen" events, in which all the visible Z0 decay products are in one hemisphere. © 1990.