We describe the pion electroproduction processes in the ∆(1232)-resonance region within the framework of chiral effective-field theory. By studying the observables of pion electroproduction in a next-to-leading order calculation we are able to make predictions and draw conclusions on the properties of the N → ∆ electromagnetic form factors.

We consider the double-spin cosφ asymmetry for pion electroproduction in semi-inclusive deep inelastic scattering of longitudinally polarized leptons off longitudinally polarized protons. We estimate the size of the asymmetry in the approximation where all twist-3 interaction-dependent distribution and fragmentation functions are set to zero. In that approximation at HERMES kinematics a sizable...

Exclusive electroproduction of a K or K * meson on the nucleon can give a Θ + pentaquark in the final state. This reaction offers an opportunity to investigate the structure of pentaquark baryons at parton level. We discuss the generalized parton distributions for the N → Θ + transition and give the leading order amplitude for electroproduction in the Bjorken regime.

Exclusive η c photo-and electroproduction at HERA as a possible probe of the odderon singularity in QCD. Abstract Theory and phenomenology of the η c photo-and electroproduction is developed from the point of view of probing the odderon singularity in QCD which corresponds to the three gluon exchange mechanism. This mechanism leads to the cross-sections which are independent of W 2 for the exch...

We analize two reactions: the electroproduction at small x and the Drell-Yan production by protons on nuclei. We show that nuclear shadowing in electroproduction is larger if the virtuality of intermediate hadrons is properly taken into account. In the Drell-Yan production, initial state interactions of fast partons are included. With this input, the excess pion contribution improves the descri...

Threshold photon electroproduction off the proton allows one to measure new electromagnetic observables which generalize the usual polarizabilities. There are – a priori – ten “generalized polarizabilities”, functions of the virtual photon mass. The purpose of this paper is to lay down the appropriate formalism to extract these quantities from the photon electroproduction cross sections. We als...

It is reported on an analysis of vector meson electroproduction at small Bjorken-x (xBj) within the handbag approach. Using a model for the generalized parton distributions (GPDs) and calculating the partonic subprocess, electroproduction off gluons, within the modified perturbative approach, cross sections and spin density matrix elements (SDME) are evaluated. The numerical results of this ana...