We present in this paper a complete study of the physical backgrounds, coherent and incoherent, in the 20-100 MeV photon spectrum from e^+e^-→π^+π^-γ at the ϕ peak, of relevance to ϕ→f₀ γ→π^+ π^- γ. Continuum contributions are suppressed by suitable kinematics and angular cuts. We show that we can determine the sign of the ϕf₀ γ coupling even for the smallest branching ratio expected for ϕ→f₀γ, thus have the promise of a totally new piece of information on the nature of the f₀.
L. et al. (Thu,) studied this question.