Matrix element corrections in top quark decays for the $$t\overline{t}W^{\pm }$$ process

AbstractWe present a method that allows enabling matrix element corrections (MECs) in Pythia8 with MC@NLO matching, without incurring double counting. MECs are an interesting feature that may contribute to the accuracy of theoretical predictions, alongside matching and merging. We directly compare our method to a specific choice of settings in Pythia8, which can remove double-counting for MECs in certain processes. We show results by taking the $$t\overline{t}W$$ t t ¯ W process as an example. This choice allows us to study the impact of decay MECs in the $$2\textrm{SS}\ell $$ 2 SS ℓ and $$3\ell $$ 3 ℓ final states. We find that jet-related observables receive these corrections unevenly throughout the phase space. They can contribute up to $$\pm 6\%$$ ± 6 % in certain regions.