the parton shower in  through the POWHEG formalism. This technique has been applied to a range of decays that occur in most of the well studied BSM scenarios. Tab. \[tab:spins\] shows the combinations of incoming and outgoing spins for which this method is used and each spin structure is implemented for the colour flows given in Tab. \[tab:colour\]. However, models with coloured tensor particles are beyond the scope of this work and therefore decays involving incoming tensor particles were limited to colour flows in which the tensor is a colour singlet.

The LO and real-emission matrix elements appearing in the POWHEG Sudakov form factor in Eq. \[eq:POSudakov\] are calculated using helicity amplitude methods to correctly incorporate spin correlations [@Richardson:2001df]. The dipole functions, $\mathcal{D}_i $, are defined as in the Catani-Seymour dipole subtraction method[@Catani:1996vz; @Catani:2002hc] when describing radiation from the decay products. In this approach, dipoles describing quasi-collinear radiation from massive vector bosons are not well defined. Therefore, the Fermion-Fermion-Vector, Scalar-Scalar-Vector and Tensor-Vector-Vector decays are limited to the situation where any final-state coloured vector particles are massless. The Vector-Fermion-Fermion and Vector-Scalar-Scalar decays do, however, include radiation from massive incoming vector particles. Decays are performed in the rest frame of the decaying 