Multiple Meson Production by Photons in Hydrogen

The analysis of 235 events of double meson production by photons with energy up to 1.1 Bev (reaction γ+p→p+π⁺+π^-) observed in a H₂ diffusion cloud chamber has produced the following results. The cross section rises rapidly at about 500 Mev to a value of approximately 70 {μ}b. The angular, momentum, and Q distributions of the reaction products cannot be satisfactorily accounted for either by a pure statistical model, or by a pure isobaric state model, or by a model assuming interaction of the incoming photon with the meson cloud of the proton, leading to π-π interaction. The observation of 14 cases of the reactions γ+p→p+π⁺+π^-+π⁰ and γ+p→n+π⁺+π⁺+π^- suggests that the combined cross section for these reactions is about 10 {μ}b between 700 and 1000 Mev.