The decay eta→π+π-π0 and the u3-term of the (3, anti 3)+(anti 3, 3) model

A detailed analysis of the decay eta → π+π-π0 is presented based on the u3-term of the (3, anti 3)+(anti 3, 3) model. A perturbation scheme is given in which π0-eta-eta' mixing is treated systematically. It is shown that the rapidly varying pole structures disappear. The slope parameter -2/μ sub(eta) is derived in a convincing way. While the rate GAMMA sub(+-0) is not determined completely, it is argued that eta-pole contribution may not be negligible and that the contribution has a possibility to save the factor 3 discrepancy of the width between the theory and the experiment. (auth.)