The Q2 Dependence of Polarized Structure Functions

A comprehensive program to measure polarized structure functions in the resonance region and beyond using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab has completed taking data. One of the experimental goals is to measure the first moment(Γ₁) of the polarized structure function, g₁, as a function of Q² by scattering polarized electrons from polarized proton (NH₃) and deuteron (ND₃) targets. Deep inelastic scattering measurements obtain positive values for the first moment at large Q². The first moment is constrained by the Gerasimov-Drell-Hearn sum rule ¹ to have a negative slope at the photon point. The CLAS measurements encompass the transition from the low Q² region dominated by resonances and other non-perturbative effects to the high Q² region where quasi-free partons dominate the interaction. Inclusive results for the double spin asymmetry A₁ and the first moment of g₁ are reported which span a range in Q² from 0.2 to 1.5 (GeV/c)² and up to W=2.5 GeV, thus probing a range in Bjorken-x from 0.04 to 0.8.