Electroproduction Of Heavy Quarkonia: Significance Of Dipole Orientation

The differential cross section d sigma/dq(2) of diffractive electroproduction of heavy quarkonia on protons is a sensitive study tool for the interaction dynamics within the dipole representation. Knowledge of the transverse momentum transfer. (q) over right arrow provides a unique opportunity to identify the reaction plane, due to a strong correlation between the directions of (q) over right arrow and impact parameter (b) over right arrow. On top of that, the elastic dipole-proton amplitude is subject to a strong correlation between (b) over right arrow and dipole orientation (r) over right arrow. Most of models for b-dependent dipole cross sections either completely miss this information, or make unjustified assumptions. We perform calculations basing on a realistic model for (r) over right arrow-(b) over right arrow. correlation, which significantly affect the q dependence of the cross section, in particular the ratio of psi'(2S) to J/psi(1S) yields. We rely on realistic potential models for the heavy quarkonium wave function and the Lorentz-boosted Schrodinger equation.