Tübingen 2003 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 32: Theorie V
HK 32.1: Gruppenbericht
Mittwoch, 19. März 2003, 14:00–14:30, D
Generalized sum rules of nucleon structure functions — •Marc Vanderhaeghen1, D. Drechsel1, C.W. Kao2, B. Pasquini3, and T. Spitzenberg1 — 1Universität Mainz — 2University Manchester — 3ECT* Trento
The way in which dispersion relations for real and virtual Compton scattering amplitudes establish connections between low energy nucleon structure quantities, such as polarizabilities or anomalous magnetic moments, and the nucleon excitation spectrum is reviewed [1]. We discuss various sum rules for forward real and virtual Compton scattering, such as the Gerasimov-Drell-Hearn sum rule and its generalizations, the Burkhardt-Cottingham (BC) sum rule, as well as new sum rules for forward nucleon polarizabilities, and review their experimental status. Furthermore, we present the predictions at low values of Q2 for these sum rules within the framework of heavy baryon chiral perturbation theory (HBChPT). In particular we show that the BC sum rule is satisfied and that the lowest moments of the spin structure g2 show a much better convergence in HBChPT than the corresponding moments of g1 [2].
[1] D. Drechsel, B. Pasquini, M. Vanderhaeghen, to appear in Phys. Rep.
[2] C.-W. Kao, T. Spitzenberg, and M. Vanderhaeghen, Phys. Rev. D (2002) in press; hep-ph/0209241.