Polarized top decay into polarized W t(↑)→W(↑)+b at O(αs)

We consider the decay of a polarized top quark into a polarized W-boson plus a bottom quark, followed by the decay of the W-boson into a pair of leptons or quarks. The: polar angle distribution of the top spin relative to the: W-momentum and the polar angle distribution of the lepton (or quark) in the W-rest frame is governed by three polarized and three unpolarized tate functions which are related to the double density matrix elements of the decay t --> W+ + b. We obtain analytical expressions for the O(alpha(5)) radiative corrections to the three polarized and three unpolarized rate functions. We also provide a comprehensive discussion of the dependence of the longitudinal, transverse and normal polarization of the top quarks produced at e(+)e(-)-colliders on beam polarization parameters. (C) 1999 Published by Elsevier Science B.V. All rights reserved.