B-hadron production in top quark decay

We present the energy distribution of b-flavoured hadrons in top quark decay using the PYTHIA and HERWIG event generators, which we tune to LEP and SLD data. We find that fitting the string and cluster models is essential to reproduce the e+e- data and to reliably predict B-hadron production in top decay. We also compare the PYTHIA and HERWIG results with the ones yielded by resummed calculations based on the fragmentation function formalism.