Isospin violation in phi, J/psi, psi '->omega pi(0) via hadronic loops

In this work, we study the isospin-violating decay of phi ->omega pi(0) and quantify the electromagnetic (EM) transitions and intermediate meson exchanges as two major sources of the decay mechanisms. In the EM decays, the present datum status allows a good constraint on the EM decay form factor in the vector meson dominance model, and it turns out that the EM transition can only account for about 1/4 similar to 1/3 of the branching ratio for phi ->omega pi(0). The intermediate meson exchanges, K (K) over bar (K*) (intermediate K (K) over bar interaction via K* exchanges), K (K) over bar*(K) (intermediate K (K) over bar* rescattering via kaon exchanges), and K (K) over bar*(K*) (intermediate K (K) over bar* rescattering via K* exchanges), which evade the naive Okubo-Zweig-Iizuka rule, serve as another important contribution to the isospin violations. They are evaluated with effective Lagrangians where explicit constraints from experiment can be applied. Combining these three contributions, we obtain results in good agreement with the experimental data. This approach is also extended to J/psi(psi')->omega pi(0), where we find contributions from the K (K) over bar (K*), K (K) over bar*(K), and K (K) over bar*(K*) loops are negligibly small, and the isospin violation is likely to be dominated by the EM transition.