  We explore the use of the Inverse Amplitude Method for unitarization of
scattering amplitudes to derive the existence and properties of possible new
heavy states associated with perturbative extensions of the electroweak
breaking sector of the Standard Model starting from the low energy effective
theory. We use a toy effective theory generated by integrating out a heavy
singlet scalar and compare the pole mass and width of the unitarized amplitudes
with those of the original model. Our results show that the Inverse Amplitude
Method reproduces correctly the singlet mass up to factors of O(1-3), but its
width is overestimated.
