Flavor-changing decays of theZ0and supersymmetry

Supersymmetric QCD violates flavor symmetry and this can permit the rare decays $Z^0$→Qq¯ through radiative corrections, where Q and q are quarks of different flavor. The most distinguishable such decay mode is found to be $Z^0$→tc¯, which could be observed at future $e^{+}$ $e^{\mathrm{-}}$ machines for some ‘‘typical’’ values of the masses of the supersymmetric particles and top quark. This is in contrast to the standard model, where the rate is very small and so the discovery of such a mode could be a dramatic indication of new physics.