On the Role of Higher Twist in Polarized Deep Inelastic Scattering

The higher twist corrections $h^N(x)/Q^2$ to the spin dependent proton and neutron structure functions $g_1^N(x, Q^2)$ are extracted in a model independent way from experimental data on $g_1^N$ and found to be non-negligible. It is shown that the NLO QCD polarized parton densities determined from the data on g1, including higher twist effects, are in good agreement with those found earlier from our analysis of the data on g1/F1 and A1 where higher twist effects are negligible. On the contrary, the LO QCD polarized parton densities obtained from the data on g1, including higher twist, differ significantly from our previous results.