By means of the Inverse Amplitude Method we unitarize the elastic
pion-nucleon scattering amplitudes obtained from Heavy Baryon Chiral
Perturbation Theory to O(q^3). Within this approach we can enlarge their
applicability range and generate the Delta(1232) resonance. We can find a
reasonable description of the pion nucleon phase shifts with (q^2) parameters
in agreement with the resonance saturation hypothesis. However, the
uncertainties in the analysis of the low energy data as well as the large
number of chiral parameters, which can have strong correlations, allow us to
obtain very good fits with rather different sets of chiral constants.Comment: Shortened version to appear in Phys. Rev. D. Brief Report
