Bottom-quark fragmentation in top-quark decay

We study the fragmentation of the b quark in top decay in NLO QCD, within the framework of perturbative fragmentation, which allows one to resum large logarithms similar to log(m(t)(2)/m(b)(2)). We show the b-energy distribution, which we compare with the exact O(alphas) result for a massive b quark. We use data from e(+)e(-) machines in order to describe the b-quark hadronization and make predictions for the energy spectrum of b-flavoured hadrons in top decay. We also investigate the effect of NLL soft-gluon resummation in the initial condition of the perturbative fragmentation function on parton- and hadron-level energy distributions. (C) 2002 Elsevier Science B.V. All rights reserved.