U-A(1) symmetry breaking and eta,eta ' mesons in the Bethe-Salpeter approach - art. no. 065201

U-A(1) symmetry breaking is studied by introducing the flavor mixing intera ction proposed by Kobayashi, Maskawa, and 't Hooft. Combining the one gluon exchange interaction, the rainbowlike Schwinger-Dyson equation and the lad derlike Bethe-Salpeter equation are derived. The anomalous PCAC relation in the frame-work of this approximation is considered. The masses of the pseu doscalar mesons pi, eta, and eta' are calculated. It is found that the pion mass is not sensitive to the strength of the flavor mixing interaction. On the other hand, the masses of eta and eta' are reproduced by a relatively weak flavor mixing interaction, for which the chiral symmetry breaking is d ominantly induced by the soft-gluon exchange interaction. The dec ay consta nts are calculated and the anomalous PCAC relation is numerically Checked. Tt is found that the flavor structures of the eta and eta' mesons significa ntly depend on their masses and therefore it is questionable to define a fa vor mixing angle for eta and eta'.