REGULARIZATION METHODS IN CHIRAL PERTURBATION-THEORY

Chiral lagrangians describing the interactions of Goldstone bosons in a theory possessing spontaneous symmetry breaking are effective, non-r enormalizable field theories in four dimensions. Yet, in a momentum ex pansion one is able to extract definite, testable predictions from per turbation theory. These techniques have yielded in recent years a weal th of information on many problems where the physics of Goldstone boso ns plays a crucial role, but theoretical issues concerning chiral pert urbation theory remain, to this date, poorly treated in the literature . We present here a rather comprehensive analysis of the regularizatio n and renormalization ambiguities appearing in chiral perturbation the ory at the one-loop level. We discuss first on the relevance of dealin g with tadpoles properly. We demonstrate that Ward identities severely constrain the choice of regulators to the point of enforcing unique, unambiguous results in chiral perturbation theory at the one-loop leve l for any observable which is free from chiral logarithmic divergences . We comment on the physical implications of these results and on seve ral possible regulating methods that may be of use for some applicatio ns.