  We show in this paper that the 1/N expansion is a reliable tool to calculate
the properties of a heavy Higgs boson. The 1/N expansion sums up all orders in
perturbation theory, and therefore avoids the renormalization scheme dependence
of the conventional perturbative approach. It is explained how effects due to
the Landau pole of the Higgs sector are isolated and subtracted, and how to
perform actual calculations, by computing the Higgs line shape for the
processes f\bar f\to H \to ZZ,f'\bar f' at next-to-leading order in the 1/N
expansion. The results are compared to the perturbative results to show the
agreement between the perturbative and the nonperturbative approach for Higgs
masses up to 1 TeV. We conclude that the theoretical predictions for Higgs
observables are well under control for the entire kinematical region of the
LHC.
