Phi-Meson Photoproduction from Nuclei

We study coherent and incoherent phi-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 omega-phi mixing. These data indicate a normal distortion of the phi-meson in nuclei, which is compatible with the results obtained through the vector meson dominance model. The data on incoherent phi-meson photoproduction show an anomalous A-dependence resulting in a very strong phi-meson distortion. These data can be explained by a coupled-channel effect through the dominant contribution from the omega -> phi or the pi -> phi transition or, more speculative, through the excitation of a cryptoexotic B (phi)-baryon