Relativistic, kinematically complete phenomenological expressions for the dilepton decay rates of nucleon resonances with arbitrary spin and parity are derived in terms of the magnetic, electric, and Coulomb transition form factors. The dilepton decay rates of the nucleon resonances with masses below 2 GeV are estimated using the extended vector meson dominance (eVMD) model for the transition f...

Compared to the case of pions the electromagnetic productions of kaons are less understood. This is due to the fact that the strangeness quantum number is explicitly present in the final state of the process. Although the reactions involving kaons are slightly more complicated, the additional degrees of freedom created by the strangeness can give information not available from nucleons and pion...

We critically review the QCD predictions for the cross sections σL and σT for diffractive ρmeson electroproduction in longitudinally and transversely polarised states in the HERA energy region. We show that both perturbative and non-perturbative approaches which involve convolution with the ρ meson wave function predict values of σT which fall-off too quickly with increasing Q2, in comparison w...

Hard exclusive electroproduction of π0, η, η mesons by the longitudinal photons is considered. With the help of the QCD factorization theorem we show that at sufficiently large virtualities Q2 amplitudes of hard exclusive processes may be calculated in terms of the target parton distributions and the minimal Fock component of the pseudoscalar meson light cone wave function at zero interquark di...

Virtual radiative corrections due to the long range Coulomb forces of heavy nuclei with charge Z may lead to sizeable corrections to the Born cross section usually used for lepton-nucleus scattering processes. An introduction and presentation of the most important issues of the eikonal approximation is given. We present calculations for forward electroproduction of rho mesons in a framework sug...

We consider the electroproduction of two vector mesons with a large rapidity gap between them on a nucleon target in the process γN → ρ1ρ2N . We calculate the Born term for this process within the collinear factorization framework. The resulting scattering amplitude may be represented as a convolution of an impact factor describing the γ → ρ1 transition and an amplitude describing the N → ρ2N ′...