Higgs boson decay in the large N limit

The Equivalence Theorem is commonly used to calculate perturbatively amplitudes involving gauge bosons at energy scales higher than gauge boson masses. However, when the scalar sector is strongly interacting the theory is non-perturbative. We show that the Equivalence Theorem holds in the large N limit at next-to-leading order by calculating the decay widths h -> W^{+}W^{-} and h->\pi^{+}\pi^{-}. We also show, in the same scheme of calculations, that unitarity is fulfilled for the process h->\pi^{+}\pi^{-}.