Determination of the gVσγ coupling constant through the process γ+N→N+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, γ+p→p+V0, V0=ρ or ω, in the collision of circularly polarized photons with a polarized proton target. In the framework of a (π+σ)-model, these asymmetries are very sensitive to the relative role of π- and σ-exchanges, in the near threshold region