Improved Unitarized Heavy Baryon Chiral Perturbation Theory for pion-nucleon Scattering to fourth order

A. Gomez Nicola, J. Nieves, J. R. Pelaez, E. Ruiz Arriola

Published 2003-12-11Version 1

We extend our previous analysis of the unitarized pion-nucleon scattering amplitude including up to fourth order terms in Heavy Baryon Chiral Perturbation Theory. We pay special attention to the stability of the generated Delta(1232 resonance, the convergence problems and the power counting of the chiral parameters.