Session D7 - Hadron Physics.
ORAL session, Saturday afternoon, May 01
Governor's Square 16, Adam's Mark Hotel
The Gerasimov-Drell-Hearn (GDH) sum rule is one of the most important tools available to study the nucleon spin structure. The GDH sum rule was initially derived for real photon absorption (corresponding to Q^2=0) and has been extended to finite Q^2. The goals of Jefferson Lab experiment E97-110 are to study the Q^2 dependence of the extended GDH integral between 0.02 and 0.3 (GeV/c)^2, the slope of the GDH integral at Q^2\sim0, and the extrapolation to the real photon point for 3He and the neutron. In this domain, the measurement of the extended GDH integral tests Chiral Perturbation Theory and checks its limits of applicability at low Q^2. The low Q^2 measurements completed in this experiment will provide new constraints on understanding the 3He and neutron spin structure and a better understanding of the effect of nucleon resonances. The data collection was completed in August of 2003, using the Jefferson Lab high polarization continuous electron beam and a polarized 3He target. The status and perspectives of the data analysis will be discussed.