Diffractive $\phi$-meson photoproduction on proton near threshold
  Photoproduction of $\phi$-meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to $E_{\gamma}$= 2.37 GeV. The differential cross sections at $t = -|t|_{min}$ do not increase smoothly as $E_{\gamma}$ increases, but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that $\phi$-mesons are photo-produced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes. 
T. Mibe, W.C. Chang, T. Nakano, D.S. Ahn, J.K. Ahn, H. Akimune, Y.   Asano, S. Date\', H. Ejiri, H. Fujimura, M. Fujiwara, K...