DETERMINATION OF ALPHA(S) AND THE NUCLEON SPIN DECOMPOSITION USING RECENT POLARIZED STRUCTURE-FUNCTION DATA

New data on polarized CL-p and e-p scattering permit a first determination of a, using the Bjorken sum rule, as well as higher precision in determining the nucleon spin decomposition. Using perturbative QCD calculations to O((alpha s/pi)(4)) for the non singlet combination of structure functions, we find alpha(s)(2.5 GeV2) = 0.375(-0.081)(+0.062), corresponding to alpha(s)(M(Z)(2)) = 0.122(-0.009)(+0.005), and using calculations to O((alpha(s)/pi)(3)) for the singlet combination we find Delta u = 0.83 +/- 0.03, Delta d = -0.43 +/- 0.03, Delta s = -0.10 +/- 0.03, Delta Sigma = Delta u + Delta d + Delta s = 0.31 +/- 0.07, at a renormalization scale Q(2) = 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 alpha(s)(M(Z)(2)) = 0.118(-0.014)(+0.007). The Delta q determinations are used to update predictions for the couplings of massive Cold Dark Matter particles and axions to nucleons.