Determination of the g(V sigma gamma) coupling constant through theprocess gamma plus N -> N plus V with circularly polarized photons

We suggest to measure the t-dependence of the two possible T-even asymmetries for the photoproduction of vector mesons, gamma + rho --> rho + V-0, V-0 = rho or omega, in the collision of circularly polarized photons with a polarized proton target. In the framework of a (pi + sigma)-model, these asymmetries are very sensitive to the relative role of pi- and sigma-exchanges, in the near threshold region