Diffractive upsilon photo-production off the proton in the QCD inspired model

Abstract

Based on the generalized vector meson dominance model in QCD, we study the photoproduction of vector meson ϒ off the proton by use of the QCD-inspired model in which the contributions from quark-quark, gluon-gluon and quark-gluon interference term to observable are taken into consideration. Calculations are performed for total cross section σ tot, differential cross section dσ/dt, ratio of the real part to imaginary part of forward scattering amplitude ρ and nuclear slop parameter function β. We analyze the individual contributions from quark gluon degrees of freedom and the QCD Odderon to the total cross section σ tot (s), differential cross section dσ/dt, ratio of the real part to imaginary part of the forward scattering amplitude ρ, and nuclear slop parameter function β. The mediators of interactions between projectiles (the quark and antiquark pair fluctuated from the real photon) and the proton target (three quark system) are the tensor Glueball and Odderon instead of using the usual Pomeron exchange. The theoretical predictions for σ tot(s) are consistent with the experimental data within error bars of the data. The data for dσ/dt, β and ρ are urgently needed. The gluon-gluon interaction makes a significant contribution to the observables while the Odderon contribution is negligibly small. Therefore, we may conclude that it is impossible to find the QCD Odderon in the γ+p → ϒ+p process as suggested before.