The mass of the vector-meson and the slope of the forward differential cross section in the photo-production process

Abstract

A simple model is given, which explains the variation of the slope of the small angle differential cross section as the mass of one of the ‘bodies’ (external mass) varies, utilizing the method removing the kinematical singularities and zeros from helicity amplitudes. From this model we can predict (a) the mass shift of the ϱ o meson produced in the process γ + P → ϱ o + P is given by and (b) ( dσ dt ) γ P → ϕ P) ⋍ 3.5 exp (3 ∼ 6)t μ b/ GeV 2 etc. The agreement of these predictions with experimental data is fairly good.