@Alioli:2009je; @Hamilton:2009za; @Re:2010bp; @Hamilton:2010mb; @Alioli:2010qp; @Alioli:2010xa; @Platzer:2011bc; @Oleari:2011ey; @Melia:2011gk; @Jager:2011ms; @Melia:2011tj; @D'Errico:2011sd; @D'Errico:2011um; @Jager:2012xk; @Re:2012zi; @Jager:2013mu], and particle decays [@LatundeDada:2008bv; @Richardson:2012bn] in the Standard Model (SM) as well as selected BSM processes [@Papaefstathiou:2009sr; @Bagnaschi:2011tu; @Klasen:2012wq; @FridmanRojas:2012yh; @Jager:2012hd]. Next-to-leading order (NLO) corrections to BSM particle decays have also previously been studied, for example in [@Horsky:2008yi] where the Supersymmetric-QCD correction to the decay $\tilde{q} \rightarrow q \tilde{\chi} $ was calculated. In this work, we present results from the implementation of the POWHEG method in  for a range of decays relevant for new physics searches. A similar approach based on generic spin structures is used to apply a matrix-element correction to hard radiation in particle decays in  [@Norrbin:2000uu].

The POWHEG formalism will be reviewed in Sect. \[sec:POWHEG\] and in Sect. \[sec:TopQuark\] our implementation of the POWHEG correction will be described in full for the example of top quark decay. In Sect. \[sec:BSMDecays\], details of the decay modes implemented will be given. The impact of the correction on the decay of the lightest graviton in the Randall-Sundrum (RS) model [@Randall:1999ee] will be studied in Sect. \[sec:RSResults\]. Finally, results from a selection of decays in the Constrained Minimal Supersymmetric Standard Model (CMSSM) will be presented 