Higgs interference effects in gg → ZZ and their uncertainty

Interference between the Standard Model Higgs boson and continuum contributions in gg -> ZZ is considered in the heavy-mass scenario. Results are available at leading order for the background (the gg -> ZZ box diagrams). It is discussed how to combine the result with the next-to-next-to-leading order Higgs production cross-section and a proposal for estimating the associated theoretical uncertainty is presented.