Diffraction production of a q(q)over-bar pair and a ρ meson on a polarized nucleon in deep-inelastic scattering

The amplitude for the diffraction dissociation of a heavy photon into a quark-antiquark pair on a polarized nucleon is calculated in the leading-logarithmic approximation of QCD. The amplitude of dissociation into a rho meson is evaluated within the hypothesis of parton-hadron duality. Spin-spin asymmetry is expressed in terms of the nucleon-spin-dependent gluon and quark structure functions (Delta G and Delta q, respectively). In view of this, the dissociation processes gamma* + p --> (<q(q)over bar>) + p and gamma* + p --> rho + p can be used to measure the spin-dependent gluon structure function Delta G(x, q(2)) in the region of small x.