On improving NLO merging for t(t)over-barW production

We introduce an improvement to the FxFx matrix element merging procedure for pp -> t((t) over bar )W production at NLO in QCD with one and/or two additional jets. The main modification is an improved treatment of jets that are not logarithmically enhanced in the low transverse-momentum regime. We provide predictions for the inclusive cross section and the t((t) over bar )W differential distributions including parton-shower effects. Taking also the NLO EW corrections into account, this results in the most-accurate predictions for this process to date. We further proceed to include the on-shell LO decays of the t((t) over bar )W including the tree-level spin correlations within the narrow-width approximation, focusing on the multi-lepton signatures studied at the LHC. We find a similar to 30% increase over the NLO QCD prediction and large non-flat K-factors to differential distributions.