The spin structure functions g_1 for the proton and the deuteron have been measured over a wide kinematic range in x and Q2 using 1.6 and 5.7 GeV longitudinally polarized electrons incident upon polarized NH_3 and ND_3 targets at Jefferson Lab. Scatt
ered electrons were detected in the CEBAF Large Acceptance Spectrometer, for 0.05 < Q^2 < 5 GeV^2 and W < 3 GeV. The first moments of g_1 for the proton and deuteron are presented -- both have a negative slope at low Q^2, as predicted by the extended Gerasimov-Drell-Hearn sum rule. The first result for the generalized forward spin polarizability of the proton gamma_0^p is also reported. This quantity shows strong Q^2 dependence at low Q^2, while Q^6gamma_0^p seems to flatten out at the highest Q^2 accessed by our experiment. Although the first moments of g_1 are consistent with Chiral Perturbation Theory (ChPT) calculations up to approximately Q^2 = 0.06 GeV^2, a significant discrepancy is observed between the gamma_0^p data and ChPT for gamma_0^p, even at the lowest Q2.
The exclusive electroproduction process $vec{e}p to e^prime n pi^+$ was measured in the range of the photon virtuality $Q^2 = 1.7 - 4.5 rm{GeV^2}$, and the invariant mass range for the $npi^+$ system of $W = 1.15 - 1.7 rm{GeV}$ using the CEBAF Large
Acceptance Spectrometer. For the first time, these kinematics are probed in exclusive $pi^+$ production from protons with nearly full coverage in the azimuthal and polar angles of the $npi^+$ center-of-mass system. The $npi^+$ channel has particular sensitivity to the isospin 1/2 excited nucleon states, and together with the $ppi^0$ final state will serve to determine the transition form factors of a large number of resonances. The largest discrepancy between these results and present modes was seen in the $sigma_{LT}$ structure function. In this experiment, 31,295 cross section and 4,184 asymmetry data points were measured. Because of the large volume of data, only a reduced set of structure functions and Legendre polynomial moments can be presented that are obtained in model-independent fits to the differential cross sections.
