Where Are the Resonances in the ρ0→π+π−γ Decay?

We consider the ρ0→π+π−γ decay to study the σ(600) and a1(1260) resonances. Using the meson dominance model we find that major effects are driven by the mass and width parameters of the σ(600), and the usually neglected contribution of the a1(1260), although small by itself, may become sizable through its interference with pion bremsstrahlung. We present a procedure to kinematically enhance the resonant effects in the angular and energy distribution of the photon.