Factorization of the Q^2 dependence in electroproduction of vector mesons

Abstract

In a framework for nonperturbative QCD calculation of high energy processes, the amplitudes for photo- and electroproduction of vector mesons are written as integrals of the overlap product of photon and vector meson wave functions, multiplied by the amplitude for the scattering of $q\bar{q}$ dipole pairs off the proton. For sizes of the overlap functions that are smaller than the typical ranges of the interaction of the dipoles with the proton, the amplitudes factorize in the form of integrals, here called overlap strengths, formed only with the overlap of the wave functions times the square of the dipole separation. The integration is extended over the light front coordinates describing the $q\bar{q}$ dipoles. With this result, the overlap strengths contain all $Q^2$ dependence of the observables. We show the importance of this factorization in the description of the experimental data for all S-wave vector mesons.