Isospin breaking and omega ->pi(+)pi(-) decay - art. no. 094013

We study omega --> pi (+)pi (-) decay up to and including all orders of the chiral expansion and one-loop level of mesons in a formalism of the chiral constituent quark model. This G-parity forbidden decay is caused by m(u) n ot equal m(d) and and the electromagnetic interaction of mesons. We illustr ate that in the formalism both the nonresonant contact interaction and rho resonance exchange contribute to this process, and the contribution from rh o resonance exchange is dominant. We obtain that the transition matrix elem ent is [rho \H-rho omega\omega] = [-(3956 +/- 280) - (1697 +/- 130)i] MeV2, and the isospin breaking parameter is m(d) - m(u) = 3.9 +/- 0.22 MeV at an energy scale of mu similar to m(omega).