Nucleonic resonance effects in the φ meson photoproduction

The process γp → φp close to threshold is investigated focusing on the role played by the sand u-channel nucleonic resonances. For this purpose, a recent quark model approach, based on the SU(6) ⊗ O(3) symmetry with an effective Lagrangian, is extended to the φ meson photoproduction. Another non-diffractive process, the tchannel π0 exchange, is also included. The diffractive contribution is produced by the t-channel Pomeron exchange. Contributions from non-diffractive sand u-channel process are found small in the case of cross sections and polarization observables at forward angles. However, backward angle polarization asymmetries show high sensitivity to this non-diffractive process. Different prescriptions to keep gauge invariance for the Pomeron exchange amplitudes are investigated. Deviations from the exact SU(6)⊗O(3) symmetry, due to the configuration mixing, are also investigated. PACS: 12.39.-x, 25.20.Lj, 13.60.Le, 13.88