Non-diffractive mechanisms in the phi-meson photoproduction on nucleons

We examine the non-diffractive mechanisms in the phi -meson photoproduction from threshold up to a few GeV using an effective Lagrangian in a constitu ent quark model. The new data from CLAS at large angles can be consistently accounted for in terms of s- and u-channel processes. Isotopic effects ari sing from the reactions gammap --> phip and gamman --> phin, are investigat ed by comparing the cross sections and polarized beam asymmetries. Our resu lt highlights an experimental means of studying non-diffractive mechanisms in phi -meson photoproduction. (C) 2001 Elsevier Science B.V. All rights re served.