Improved treatment of loop diagrams in SU(3) baryon chiral perturbation theory

Abstract

Baryon chiral perturbation theory as conventionally applied has a well-known problem with the SU(3) chiral expansion in that loop diagrams generate very large SU(3) breaking corrections and greatly upset the subsequent phenomenology. We argue that the problem comes from the portions of loop integrals corresponding to propagation at such short distances that the effective theory is not valid. One can reformulate the theory equally rigorously by regulating the loop integrals using a momentum-space cutoff which removes the spurious short-distance physics. We show that this reformulation improves the phenomenology for reasonable values of the cutoff.