QCD evolution of the spin structure functions of the neutron and proton

Models of the long-distance behavior of QCD can be used to make predictions for the twist-two piece of the current correlation function appearing in deep-inelastic scattering. The connection between the model predictions, valid at a four-momentum transfer squared Q² of the order of 1 (GeV/c)², and the data, collected at much higher Q², is provided by perturbative QCD. We present here the details of a method, previously used for spin-averaged lepton scattering, applied to the spin-dependent case. We then use the method to make predictions for the spin structure functions gₗᵖʳᵒᵗᵒⁿ and gₗⁿᵉᵘᵗʳᵒⁿ.