Measurement of weak couplings through toponium decays

Abstract We study weak decays of a single quark in toponium and show that these decay modes can be used to measure the strength of the (tbW) coupling. Already for a toponium of 50 GeV, semileptonic decays can be detected through their yield of hard leptons, and non-leptonic decays through their contribution to non-planar events. Single quark decays can, furthermore, serve to determine the polarization of toponium and thus measure the vector part of the neutral current coupling to heavy quarks.