Simulation of Finite Width Effects in Physics Beyond the Standard Model

We present a method for the inclusion of finite width effects in the simulation of Beyond Standard Model (BSM) physics. In order to test the validity of the method we compare our results with matrix elements for a range of production and decay processes in the Standard Model, Minimal Supersymmetric Standard Model (MSSM) and Minimal Universal Extra Dimensions model (MUED). This procedure has been implemented in the Herwig++ event generator and will be available in a forthcoming release.