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 ∼ log(mt2/mb2). We show the b-energy distribution, which we compare with the exact O(αS) 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