Impact of hadronic and nuclear corrections on global analysis of spin-dependent parton distributions

We present the first results of a new global next-to-leading order analysis of spin-dependent parton distribution functions from the most recent world data on inclusive polarized deep-inelastic scattering, focusing in particular on the large-x and low-Q² regions. By directly fitting polarization asymmetries we eliminate biases introduced by using polarized structure function data extracted under nonuniform assumptions for the unpolarized structure functions. For analysis of the large-x data we implement nuclear smearing corrections for deuterium and ³He nuclei, and systematically include target mass and higher twist corrections to the g₁ and g₂ structure functions at low Q². We also explore the effects of Q² and W² cuts in the data sets, and the potential impact of future data on the behavior of the spin-dependent parton distributions at intermediate and large x.