Threshold behaviour of top production in e+e− annihilation

Abstract Implications of electroweak interactions on the threshold behaviour of top production are analyzed. Weak decays of densely spaced high radial excitations of toponium lead to a form of the cross section below threshold that is difficult to distinguish from continuum production. We study the contribution of the vector and axial-vector current to the continuum and calculate the rate for Z decays into top particles as a function of the top quark mass, including QCD corrections.