An isotopic effect in phi photoproduction at a few GeV
  A distinct isotopic effect in phi photoproduction at 2-5 GeV region is identified by examining the production amplitudes due to Pomeron-exchange and meson-exchange mechanisms. This effect is mainly caused by the pi-eta interference constrained by SU(3) symmetry and the isotopic structure of the gamma NN coupling in the direct phi-radiation amplitude. It can be tested experimentally by measuring differences in the polarization observables between the gamma-p and gamma-n reactions. 
A.I.Titov(JINR,Dubna), T.-S.H.Lee(ANL,Argonne) and   H.Toki(RCNP,Osaka-U)