TOP-QUARK PAIR PRODUCTION AND DECAY NEAR-THRESHOLD IN E(-) COLLISIONS()E()

We review the physics involved in the production and decay of top quar ks in e(+)e(-) --> t (t) over bar near threshold, with special emphasi s on the recent theoretical study on the decay process of top quarks i n the threshold region. The energy-angular distribution of l(+) in sem ileptonic top decays is calculated including the full O(alpha(s)) corr ections. Various effects of the final-state interactions are elucidate d. A new observable is defined near threshold, which depends only on t he decay of fr ee polarized top quarks, and thus it can be calculated without bound-state effects or the final-state interactions.