Z0-boson production in association with a t(t)over-bar pair at next-to-leading order accuracy with parton shower effects

We present predictions for the production cross section of a standard model Z(0) boson in association with a t (t) over bar pair at the next-to-leading order accuracy in QCD, matched with shower Monte Carlo programs to evolve the system down to the hadronization energy scale. We adopt a framework based on three well-established numerical codes, namely, the POWHEG-BOX, used for computing the cross section, HELAC-NLO, which generates all necessary input matrix elements, and finally a parton shower program, such as PYTHIA or HERWIG, which allows for including t-quark and Z(0)-boson decays at leading-order accuracy and generates shower emissions, hadronization and hadron decays.