The analysis of exclusive meson leptoproduction (DVMP) within the handbag approach is reviewed and the parametrization of the generalized parton distributions (GPDs) is discussed in some detail with the main interest focused of the GPDs H and E. Appl
ications of the GPDs extracted from DVMP to other hard exclusive processes as for instance deeply virtual Compton scattering (DVCS) and an evaluation of Jis sum rule are also presented.
It is reported on an analysis of electroproduction of light mesons at small Bjorken-x within the handbag approach. The partonic subprocesses, meson electroproduction off quarks or gluons, are calculated within the modified perturbative approach in wh
ich quark transverse momenta are retained. The soft hadronic matrix elements, generalized parton distributions, are constructed by means of double distributions. The constraints from parton distributions and sum rules are taken into account. Various moments of these generalized parton distributions are compared to recent results from lattice gauge theories.
In this talk various spin effects in hard exclusive electroproduction of mesons are briefly reviewed and the data discussed in the light of recent theoretical calculations within the frame work of the handbag approach. For electroproduction of positi
vely charged pions it is shown that there is a strong contribution from photon-pion transitions which can be modeled by the transversity GPD H_T accompanied by the twist-3 pion wave function.
In this talk various spin effects in hard exclusive electroproduction of mesons are briefly reviewed. The data are discussed in the light of recent theoretical calculations within the frame work of the handbag approach.
Hard exclusive pi+ electroproduction is investigated within the handbag approach. The prominent role of the pion-pole contribution is demonstrated. It is also shown that the experimental data require a twist-3 effect which ensues from the helicity-fl
ip generalized parton distribution H_T and the twist-3 pion wave function. The results calculated from this handbag approach are compared in detail with the experimental data on cross sections and spin asymmetries measured with a polarized target. It is also commented on consequences of this approach for exclusive pi^0 and vector-meson electroproduction.
It is reported on a global analysis of hard vector-meson electroproduction which is based on the handbag factorization. The generalized parton distributions are constructed from their forward limits with the help of double distributions and the parto
nic subprocesses are calculated within the modified perturbative approach.
Electroproduction of light vector mesons is analyzed on the basis of handbag factorization. The required generalized parton distributions are constructed from the CTEQ6 parton distributions with the help of double distributions. The partonic subproce
sses are calculated within the modified perturbative approach. The present work extends our previous analysis of the longitudinal cross section to the transverse one and other observables related to both the corresponding amplitudes. Our results are compared to recent experimental findings in detail.
The various factorization schemes for hard exclusive processes and the status of their applications is briefly reviewed.
