New parton distributions from large-$x$ and low-$Q^2$ data

We report results of a new global next-to-leading order fit of parton distribution functions in which cuts on $W$ and $Q$ are relaxed, thereby including more data at high values of $x$. Effects of target mass corrections, higher twist contributions, and nuclear corrections for deuterium data are significant in the large-$x$ region. The leading twist parton distributions are found to be stable to target mass correction model variations as long as higher twist contributions are also included. The behavior of the $d$ quark as $x\ensuremath{\rightarrow}1$ is particularly sensitive to the deuterium corrections, and using realistic nuclear smearing models the $d$-quark distribution at large $x$ is found to be softer than in previous fits performed with more restrictive cuts.