Matrix element corrections to parton shower simulations of heavy quark decay

Parton showers are accurate for soft and/or collinear emission, but for a g ood description of the whole of phase space they need to be supplemented by matrix element corrections. In this paper, we discuss matrix element corre ctions to the decay t --> Wb and apply our results to the HERWIG Monte Carl o event generator. The phenomenological results show marked improvement rel ative to previous versions and agree well with the exact first-order matrix -element calculation. (C) 1998 Elsevier Science B.V. All rights reserved.