  We derive a nonperturbative result for the Higgs propagator by calculating
the NLO correction in the 1/N expansion of O(N) sigma models. For dealing with
the 1/N expansion beyond leading order, we develop techniques to calculate
certain infinite sets of multiloop Feynman diagrams. We then calculate the
Higgs lineshape in fermion scattering, as seen for instance at a muon collider.
We compare with the existing two-loop perturbative results. There is a
considerable discrepancy between perturbation theory and the 1/N expansion in
LO. By including the NLO correction, this discrepancy is reduced dramatically.
The results are in very good agreement with the two-loop result even for masses
as high as 850 GeV. A maximum of the mass is reached at 930 GeV. For
phenomenological purposes, we give a simple approximate relation between the
Higgs mass and width.
