Gauge-Independent Bound-State Corrections to the Toponium Decay Width

Abstract

Off-shell and relativistic bound-state corrections for the decay $t\to b+W$ are calculated to $O({\text{a}}_s^2)$ making full use of the Bethe-Salpeter formalism for weakly bound systems. Thus we are able to take into account all terms to that order in a systematic and straightforward manner. One of the previously not considered contributions cancels precisely gauge dependent terms which appeared in an earlier off-shell calculation. Important cancellations also determine the gauge-independent part.

Comments: 4 pages, TUW-94-16