Flavor mixing in the low energy hadron dynamics: Interplay of theSU f (3) breaking and theU A (1) anomaly

Abstract

We extend our previous investigation about the flavor mixing or the OZI violating process in the light quark systems with the use of the generalized Nambu-Jona-Lasinio model incorporating theU A (1) anomaly. The OZI breaking effects newly studied in the meson sector include the η and η′ meson decay constants, their couplings with nucleon as well as the masses and the mixing property of the scalar mesons. As for the baryon sector, we reexamine the strangeness content of the proton and the π-N sigma term∑πN by taking into account the interactions between the constituent quarks. It is found that the short-range spin-spin interaction between the quarks gives anO(10 MeV)-enhancement for the theoretical value of the sigma term. Anomalous quark contents of other octet and decuplet baryons (hyperons) are also examined. It is shown that the axial anomaly induces the anomalous quark contents which are not expected in the naive quark model, while the short-range interaction between the quarks acts to suppress (enhance) the quark contents of the decuplet (octet) baryons. All the results indicate that the following picture holds systematically:m s is so large that (i) the strangeness mixing induced by the anomaly is considerably suppressed and that (ii) the naive chiral perturbation does not work in the strange sector even in the tree level of the meson fields (largeN c limit). The spin problem of nucleon, which is another subject related to the flavor mixing, is also examined with the use of our effective model.