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

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

A. Accardi, M. E. Christy, C. E. Keppel, W. Melnitchouk, P. Monaghan, J. G. Morfín, and J. F. Owens

Phys. Rev. D 81, 034016 – Published 11 February 2010

Abstract

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 $x \to 1$ 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.