Top quark pair production in association with a Z-boson at next-to-leading-order 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 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.