2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46253Heavy baryon chiral perturbation theory is briefly reviewed, paying particular attention to the role of the spin 3/2 delta resonances. The concept of resonance saturation for the baryonic sector is critically discussed. Starting from a relativistic formulation of the pion-nucleon-delta system, the heavy baryon chiral lagrangian including spin 3/2 resonances is constructed by means of a 1/m-expansion. The effective theory obtained admits a systematic expansion in terms of soft momenta, the pion mass $M_π$ and the delta-nucleon mass difference $Δ$.14 pages, 3 postscript figures, talk given at the 7th International Conference on the Structure of Baryons, Santa Fe, NM, 3-7 Oct 1995High Energy Physics - PhenomenologyNuclear Theorytext