MAID is a unitary isobar model for a partial wave analysis of pion photoand electroproduction in the resonance region. It is fitted to the world data and can give predictions for multipoles, amplitudes, cross sections and polarization observables in the energy range from pion threshold up to W = 2 GeV and photon virtualities Q < 5 GeV. Using more recent experimental results from Mainz, Bates, B...

We estimate the leading order amplitudes for exclusive photon and meson electroproduction reactions at large Q2 in the valence region in terms of skewed quark distributions. As experimental investigations can currently only be envisaged at moderate values of Q2 , we estimate power corrections due to the intrinsic transverse momentum of the partons in the meson wavefunction and in the nucleon. T...

Electroproduction of two mesons well separated in rapidity allows the first feasible selective access to chiral-odd transversity GPDs provided one of these mesons is a transversely polarized vector meson ρT .

Azimuthal single-spin asymmetries (SSA) in semi-inclusive electroproduction of charged pions and kaons in deep-inelastic scattering of positrons on a transversely polarised hydrogen target were observed. SSA amplitudes for both the Collins and the Sivers mechanism are presented.

In the framework of semihard QCD approach, with the emphasis on the BFKL evolution of gluon distributions, we calculate the differential cross sections of inclusive D mesons electroproduction at HERA and confront our results with available ZEUS experimental data.

We review recent results on the inclusive electroproduction of light hadrons at next-toleading order in the parton model of quantum chromodynamics implemented with fragmentation functions and present updated predictions for HERA experiments based on the new AKK set.

We review some techniques of resummation applied to heavy quark production in hadronic scattering and electroproduction near partonic threshold, and discuss the reduction of factorization scale dependence in resummed cross sections.

The unitary isobar model MAID has been extended and used for a partial wave analysis of pion photoand electroproduction in the resonance region W < 2 GeV. Older data from the world data base and more recent experimental results from Mainz, Bates, Bonn and JLab for Q up to 4.0 (GeV/c) have been analyzed and the Q dependence of the helicity amplitudes have been extracted for a series of four star...

Exclusive electroproduction of vector mesons (VMs) is a particularly good process for studying the transition from the soft to the hard regime of strong interactions [1], the former being well described within the Regge phenomenology while the latter by perturbative QCD (pQCD). The interest in this interplay comes from the need to understand at which scale a partonic language is applicable. The...

We have extended a model for the γN → ππN reaction to virtual photons and selected the diagrams which have a ∆ in the final state. The agreement found with the γ v p → ∆ 0 π + and γ v p → ∆ ++ π − reactions is good. The sensitivity of the results to N ∆ transition form factors is also studied. The present reaction, selecting a particular final state, is an extra test for models of the γ v N → π...