Double-spin asymmetries in the cross section of electroproduction of ρ and φ mesons on the proton and deuteron are measured at the HERMES experiment. The photoabsorption asymmetry in exclusive ρ electroproduction on the proton exhibits a positive tendency. This is consistent with theoretical predictions that the exchange of an object with unnatural parity contributes to exclusive ρ electroprodu...

We use perturbative QCD and parton-hadron duality to estimate the cross sections for the diffractive electroproduction of ρ ′ (1 −) and ρ(3 −) resonances which occur in the 1.3– 1.8 GeV mass interval. We present the cross sections and the ratios σ L /σ T as a function of Q 2. We compare the predictions with those for the diffractive electroproduction of ρ mesons. We show how such diffractive el...

Photo-and electroproduction of η, η ′ mesons on protons are investigated within a relativistic chiral unitary approach based on coupled channels. The s wave potentials for electroproduction and meson-baryon scattering are derived from a chiral effective Lagrangian which includes the η ′ as an explicit degree of freedom and incorporates important features of the underlying QCD Lagrangian such as...

The photo-and electroproduction of the η, η ′ mesons on nucleons are investigated within a relativistic chiral unitary approach based on coupled channels. The s-wave potentials for electroproduction and meson-baryon scattering are derived from a chiral effective Lagrangian which includes the η ′ as an explicit degree of freedom and incorporates important features of the underlying QCD Lagrangia...

A Pomeron-exchange model of exclusive electroproduction of ρ-mesons is examined using a dressed-quark propagator. It is shown that by representing the photonρ-meson-Pomeron coupling by a nonperturbative, confined-quark loop, one obtains predictions for ρ-meson electroproduction that are in good agreement with experiment.

We analyze a low-energy theorem of threshold pion electroproduction which allows one to determine the charge radius of the pion. We show that at the same order where the radius appears, pion loops induce a correction to the momentum dependence of the longitudinal dipole amplitude L01 (2) . This model-independent correction amounts to an increase of the pion charge radius squared from the electr...

A systematic multiple scattering formalism for vector meson electroproduction from nuclei is developed, with emphasis on the formation, propagation and hadronization scales for quark-gluon fluctuations of the virtual high-energy photon. The theory is compared to HERMES measurements of ρ electroproduction on 14 N. The nuclear transparency as a function of the vector meson propagation length is w...

We compute the exclusive electroproduction, $\gamma^* p \rightarrow V p$, of heavy quarkonia $V$ to NLO in collinear factorisation scheme, which has been formally proven for this process. The inclusion an off-shell virtuality $Q^2$ carried by photon extends photoproduction phase space observable electroproduction kinematics. This process is relevant diffractive scattering at HERA and upcoming E...

We argue that the electroproduction of exotic particles is a useful tool for study of their partonic structure. In the case of hybrid mesons, the magnitude of their cross sections shows that they are accessible for measurements in existing electroproduction experiments.