Measurements of the Q2-dependence of the proton and deuteron spin structure functions g1p and g1d

Abstract The ratio g 1 F 1 has been measured over the range 0.03 x Q 2 c ) 2 using deep-inelastic scattering of polarized electrons from polarized protons and deuterons. We find g 1 F 1 to be consistent with no Q 2 -dependence at fixed x in the deep-inelastic region Q 2 > 1 ( GeV / c ) 2 . A trend is observed for g 1 F 1 to decrease at lower Q 2 . Fits to world data with and without a possible Q 2 -dependence in g 1 F 1 are in agreement with the Bjorken sum rule, but Δ q is substantially less than the quark-parton model expectation.