Moments of the spin structure functions g1p and g1d for 0.05<Q2<3.0 GeV2

The spin structure functions g1 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 NH3 and ND3 targets at Jefferson Lab. Scattered electrons were detected in the CEBAF Large Acceptance Spectrometer, for 0.05<Q2<5 GeV2 and W<3 GeV. The first moments of g1 for the proton and deuteron are presented - both have a negative slope at low Q2, as predicted by the extended Gerasimov-Drell-Hearn sum rule. The first extraction of the generalized forward spin polarizability of the proton γ0p is also reported. This quantity shows strong Q2 dependence at low Q2. Our analysis of the Q2 evolution of the first moment of g1 shows agreement in leading order with Heavy Baryon Chiral Perturbation Theory. However, a significant discrepancy is observed between the γ0p data and Chiral Perturbation calculations for γ0p, even at the lowest Q2