Top quark pair production in association with a Z-boson at NLO accuracy
  We present predictions for the production cross section of t-quark pair production in association with a Z boson at the next-to-leading order (NLO) accuracy using matrix elements obtained from the HELAC-Oneloop package. We use the subtraction method for computing the radiative corrections as implemented in the POWHEG-Box, which was also used in several other computations of similar complexity. 
Adam Kardos, Costas Papadopoulos and Zolt\'an Tr\'ocs\'anyi
hep-ph