A Theoretical Study of $ρ^{0}$-Photoproduction on Nucleons near Threshold

Abstract

We investigate the possibility that the process of $ρ^{0}$-meson photoproduction on proton, $γ+p\to p+ρ^{0}$, in the near threshold region $E_γ< 2$ GeV, can be considered in the framework of model with $π$-, $σ$- and N-exchanges. This suggestion is based on a study of the t-dependence of differential cross section, $dσ(γp \to p ρ^{0})/dt$, which has been measured by SAPHIR Collaboration. We find that the suggested model provides a good description of the experimental data with new values of $ρNN$-coupling constants in the region of the time-like $ρ^{0}$-meson momentum. Our results suggest that such model can be considered as a suitable nonresonant background mechanism for the future discussion of possible role of nucleon resonance contributions. Our predictions for $ρ^{0}$-meson photoproduction on neutron target and for beam asymmetry on both proton and neutron targets are presented.

21 pages, RevTex, 6 PS figures