New JAM global analysis of spin-dependent parton distributions

We present the results of a new global next-to-leading order analysis of spin-dependent parton distribution functions from the most recent world data on polarized deep-inelastic scattering (DIS) and $pp$ collisions, focusing in particular on the large-$x$ and low-$Q^2$ regions. By directly fitting DIS 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 $^3$He nuclei, and systematically include target mass and higher twist corrections to the $g_1$ and $g_2$ structure functions at low $Q^2$. We also explore the effects of $Q^2$ and $W^2$ 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 $x$.