Vector mesons $\rho ,{\rho }^{\prime }$ and ${\rho }^{\prime \prime }$ diffractively photo- and leptoproduced

Abstract

In the framework of non-perturbative QCD we calculate high-energy diffractive production of vector mesons $\text{rh},{\text{rh}}^{\prime }$ and ${\text{rh}}^{\prime \prime }$ by real and virtual photons on a nucleon. The initial photon dissociates into a $q\bar{q}$-dipole and transforms into a vector meson by scattering off the nucleon which, for simplicity, is represented as quark-diquark. The relevant dipole-dipole scattering amplitude is provided by the non-perturbative model of the stochastic QCD vacuum. The wave functions result from considerations in the frame of light-front dynamics; the physical ${\text{rh}}^{\prime }$- and ${\text{rh}}^{\prime \prime }$-mesons are assumed to be mixed states of an active 2S-excitation and some residual rest (2D- and/or hybrid state). We obtain good agreement with the experimental data and get an understanding of the markedly different ${\pi }^{+}{\pi }^{-}$-mass spectra for photoproduction and $e^{+}{e}^{-}$-annihilation.

Comments: 6 pages, LaTeX2e, 6 ps/eps figures included, to be published in Fizika B