A modern view of wide-angle exclusive scattering

The basic theoretical ideas of the handbag mechanism for wide-angle exclusive scattering reactions are discussed and, with regard to the present experimental program carried out at JLab, its application to Compton scattering is reviewed in some detail. Results for other wide-angle reactions such as two-photon annihilations into pairs of hadrons or virtual Compton scattering are presented as well.Comment: 10 pages, 6 figures (using LATEX with ws-procs9x6.cls), talk presented at the Nstar2002 workshop on the physics of excited nucleons, Pittsburgh, October 200

The GPD H-tilde and spin correlations in wide-angle Compton scattering

Wide-angle Compton scattering (WACS) is discussed within the handbag approach in which the amplitudes are given by products of hard subprocess amplitudes and form factors, specific to Compton scattering, which represent 1/x-moments of generalized parton distributions (GPDs). The quality of our present knowledge of these form factors and of the underlying GPDs is examined. As will be discussed in some detail the form factor R_A and the underlying GPD H-tilde are poorly known. It is argued that future data on the spin correlations A_{LL} and/or K_{LL} will allow for an extraction of R_A which can be used to constrain the large -t behavior of H-tilde.Comment: 27 pages, 10 figure