Determination of αs and the nucleon spin decomposition using recent polarized structure function data

New data on polarized μ−p and e−p scattering permit a first determination of αs using the Bjorken sum rule, as well as higher precision in determining the nucleon spin decomposition. Using perturbative QCD calculations to for the non-singlet combination of structure functions, we find αs(2.5 GeV2) = 0.375−0.081+0.062, corresponding to αs(MZ2) = 0.122−0.009+0.005, and using calculations to for the singlet combination we find Δu = 0.83 ± 0.03, Δd = −0.43 ± 0.03, Δs = −0.10±0.03, ΔΣ  Δu + Δd + Δs = 0.31 ± 0.07, at a renormalization scale Q2 = 10 GeV2. Perturbative QCD corrections play an essential role in reconciling the interpretations of data taken using different targets. We discuss systematic uncertainties in the above numbers, which are dominated by higher-twist effects and lead, we estimate, to αs(MZ2) = 0.118−0.014+0.007. The Δq determinations are used to update predictions for the couplings of massive Cold Dark Matter particles and axions to nucleons.