Once more on search forq ² q ⁻²-states in photon-photon collisions

Abstract

It is shown that the JADE group upper limits for σ(γγ→ρ⁰ω) do not lead to any serious conclusions about the$q^2 \bar q^2$-resonance production in this reaction. The predictions for the processes$\gamma \gamma \to q^2 \bar q^2 \to \rho ^0 \omega$ and$\gamma \gamma \to q^2 \bar q^2 \to \rho ^0 \varphi$ are discussed in detail. It is noted that one of some assumptions, which are made to extract the processγγ→ρ ⁰ ρ ⁰ from γγ→4π, is wrong from the theoretical point of view and the other appears to be unsound. It is shown that theq ² q ⁻²-resonance production can describe all features of the reactionsγγ→ρ ⁰ ρ ⁰ andγγ→ρ ⁺ ρ ^- qualitatively and quantitatively. It is emphasized that the production of the exotic resonance withI=2 and the resonance (or a few ones) withI=0, having close masses, provides the enhancement in σ(γγ→ρ ⁰ ρ ⁰) and the absence of the similar enhancement in σ(γγ→ρ ⁺ ρ ^-) in the vector meson dominance model frame.