NONRELATIVISTIC CHIRAL EXPANSION AND NONLEPTONIC DECAYS OF OCTET AND DECUPLET BARYONS

We discuss the chiral lagrangian for J(P) = 1/2+ octet and J(P) = 3/2+ decuplet baryons in the language of the heavy particle effective theory. We show that the effective theory qualitatively reproduces the Pauli amplitudes for the nonleptonic hyperon decays, calculated recently by Trofimenkoff. We discuss the relation of our results to nonrelativistic SU(6). We argue that we can consistently classify the meson-baryon interaction terms in lowest order in the momentum expansion according to their transformation properties under nonrelativistic SU(6). Nevertheless, the theory as a whole remains explicitly Lorentz invariant. We explain why this does not run afoul of the theorems concerning interacting relativistic SU(6) theories. We use this SU(6) classification to discuss the relation between the nonleptonic OMEGA--decays and the nonleptonic decays of the octet baryons. We find that the OMEGA--decays cannot be explained by any interaction term transforming simply under SU(6) because the nonleptonic OMEGA--decays do not display the pronounced DELTA-I = 1/2 enhancement seen in the octet hyperon decays. Any explanation of the OMEGA--decays requires a fine tuning of the parameters in the effective theory. We speculate that this problem may point to a flaw in the basic assumption that DELTA-I = 1/2 four-quark operators, universally enhanced by QCD, are the dominant mechanism behind the DELTA-S = 1 nonleptonic decays.