We review the main results of next-to-leading order QCD analyses of polarized deepinelastic scattering data, with special attention to the assessment of theoretical uncertainties.
1o Experimental information on deeply inelastic scattering (DIS) of polarized leptons off polarized nucleon targets has greatly improved since the first E80/E130 experiments at SLAC (see ref.
[1] for a complete bibliography.) While at an early stage the attention was mainly focused on the test of the Ellis-Jaffe [2] sum rule, more recently the interest is concentrated on the study of the general features of polarized nucleons in the deep-inelastic region in the context of the QCD-improved parton model. The analysis of polarized DIS data can at present be performed using perturbative QCD at next-to-leading order accuracy, thanks to the recent computation [3] of order c~ Altarelli-Parisi splitting functions in the polarized case. This analysis has been performed by many different authors [1],[4]-[10] with consistent results. I will present here the results obtained in ref. . The strategy is the same as the one adopted in the case of unpolarized DIS: the polarized parton distributions Aq(x, Q2), Ag(x, Q2) at an initial scale Q0 are assumed to have an arbitrar-