Vector-meson electroproduction from generalized vector dominance

Abstract

Including destructively interfering off-diagonal transitions of diffraction-dissociation type, we arrive at a formulation of GVD for exclusive vector-meson production in terms of a continuous spectral representation of dipole form. The transverse cross-section, σ T,γ ∗ p→V p , behaves asymptotically as 1/ Q 4, while R V≡σ L,γ ∗ p→V p /σ T,γ ∗ p→V p becomes asymptotically constant. Contributions violating s-channel helicity conservation stay at the level established in low-energy photoproduction and diffractive hadron–hadron interactions. The data on ρ 0-meson production from the Fermilab E665 Collaboration and on φ- and ρ 0-meson production from HERA are found to be in agreement with these predictions.