Münster 2002 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 2: Theory I
HK 2.6: Talk
Monday, March 11, 2002, 18:15–18:30, A
Dispersion relations in real and virtual Compton scattering — •Marc Vanderhaeghen1, Dieter Drechsel1, Michael Gorchtein1, Andreas Metz2, and Barbara Pasquini3 — 1Johannes Gutenberg University Mainz — 2Vrije Universteit Amsterdam — 3ECT* Trento
A unified presentation is given of the use of dispersion relations in the real and virtual Compton scattering processes off the nucleon. It is reviewed how for Compton scattering, dispersion relations establish a connection between low energy nucleon structure quantities such as its polarizabilities on the one hand and the nucleon excitation spectrum on the other hand. Various types of dispersion relations are subsequently discussed for the real Compton scattering (RCS) process as a tool to extract nucleon polarizabilities from RCS data and the present knowledge on the nucleon polarizabilities obtained in this way is reviewed [1]. Subsequently, we present the extension of the dispersion relation formalism to the virtual Compton scattering (VCS) process as a tool to extract generalized polarizabilities of the nucleon [2]. The information on generalized nucleon polarizabilities as extracted in this way from recent VCS experiments is reviewed in particular in view of new JLab VCS data for photon virtualities Q2 in the range 1 - 2 GeV2.
[1] D. Drechsel, B. Pasquini and M. Vanderhaeghen, in preparation
[2] B. Pasquini et al., Eur.Phys.J.A 11 (2001) 185.