Heavy Baryon Chiral Perturbation Theory and the Spin 3/2 Delta Resonances

Abstract

Heavy 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 $M_{\pi }$ and the delta-nucleon mass difference $\Delta$.

Comments: 14 pages, 3 postscript figures, talk given at the 7th International Conference on the Structure of Baryons, Santa Fe, NM, 3-7 Oct 1995