ELECTROWEAK CORRECTIONS TO THE TOPONIUM DECAY WIDTH

We discuss one-loop electroweak corrections to the decay width of topo nium. We calculate the energy-level shifts by expanding around the sol ution of the Bethe-Salpeter equation in the instantaneous approximatio n, in analogy with the positronium case. We show that first-order elec troweak effects are suppressed by at least four powers of the strong c oupling constant, and are therefore negligible compared with QCD corre ctions. The calculation is manifestly gauge invariant and takes into a ccount the contributions to the decay rate due to both Coulomb enhance ment and phase space reduction effects.