Anomalous top couplings in WHIZARD

The origin of the quark mass hierarchy within the Standard Model (SM) is still very unclear, whereas the top quark is particularly interesting because of its uniquely large mass, which has also made it hard to access experimentally so far. At the LHC, however, large abundances of top quarks will be produced over the next years, providing the statistics necessary to measure various properties of the top quark with high precision. Within the approach of effective operators, it is possible to parameterize any new physics contributing to top interactions via anomalous top-gauge boson couplings ttγ, ttZ, tbW and ttg, whereas contact terms (e. g. ttgg) have to be included in general to ensure gauge invariance. The full set of gauge-invariant operators leading to anomalous top couplings has been implemented into the parton-level Monte Carlo generator WHIZARD to provide a consistent tool for MC studies of full hard scattering amplitudes relevant at the detector level. We show results discussing the influence of contributions required by gauge invariance, and also the validity of the usual on-shell approximation for more complex final states.