φ-meson photoproduction from nuclei

We study coherent and incoherent φ-meson photoproduction from nuclei. The available data are analyzed in terms of single and coupled channel photoproduction. It is found that the data on coherent photoproduction can be well reproduced within a single channel optical model and show only little room for ω− φ mixing. These data indicate a normal distortion of the φ-meson in nuclei, which is compatible with the results obtained through the vector meson dominance model. The data on incoherent φ-meson photoproduction show an anomalous A-dependence resulting in a very strong φ-meson distortion. These data can be explained by a coupled channel effect through the dominant contribution from the ω → φ or π→φ transition or, more speculative, through the excitation of a cryptoexotic Bφbaryon. PACS. 11.80.Gw Multichannel scattering – 12.40.Vv Vector-meson dominance – 13.60.-r Photon and charged-lepton interactions with hadrons – 25.20.Lj Photoproduction reactions