Gómez Nicola, ÁngelNieves, J.Peláez Sagredo, José RamónRuiz Arriola, E.2023-06-202023-06-202004-03-010556-282110.1103/PhysRevD.69.076007https://hdl.handle.net/20.500.14352/51400© 2004 The American Physical Society. This work was supported in part by funds provided by the Spanish DGI with Grant Nos. FM2002-03218, BFM2000- 1326 and BFM2002-01003; CICYT Grant No. FPA2000- 0956; Junta de Andalucía Grant No. FQM-225 and EURIDICE with contract number HPRN-CT-2002-00311.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.spajournal articlehttp://dx.doi.org/10.1103/PhysRevD.69.076007http://journals.aps.orgopen access51-73Nucleon scatteringFísica-Modelos matemáticosFísica matemática