A consistent description of ρ⁰→ ππγ decays including σ(500) meson effects

A consistent description of σ(500) meson effects in ρ0→ π0π0γ and π+π-γ decays is proposed in terms of reasonably simple amplitudes which reproduce the expected chiral-loop behaviour for large mσvalues. For the neutral case, in addition to the well known ω exchange, there is an important contribution from the σ(500) meson that is in agreement with recent experimental data. For the charged case, where the dominant contribution comes from bremsstrahlung, the effects of the σ(500) meson are relevant only at high values of the photon energy and compatible with present data. A combined analysis of both processes with moderately improved experimental information should contribute decisively to clarify the status of this controversial σ(500) meson. © SISSA/ISAS 2004.