  We use the POWHEG formalism in the Herwig++ event generator to match QCD
real-emission matrix elements with the parton shower for a range of decays
relevant to Beyond the Standard Model physics searches. Applying this
correction affects the shapes of experimental observables and so changes the
number of events passing selection criteria. To validate this approach, we
study the impact of the correction on Standard Model top quark decays. We then
illustrate the effect of the correction on Beyond the Standard Model scenarios
by considering the invariant-mass distribution of dijets produced in the decay
of the lightest Randall-Sundrum graviton and transverse momentum distributions
for decays in Supersymmetry. We consider only the effect of the POWHEG
correction on the simulation of the hardest emission in the shower and ignore
the normalisation factor required to correct the total widths and branching
ratios to next-to-leading order accuracy.
