<x>_{u-d} from lattice QCD at nearly physical quark masses
  We determine the second Mellin moment of the isovector quark parton distribution function <x>_{u-d} from lattice QCD with N_f=2 sea quark flavours, employing the non-perturbatively improved Wilson-Sheikholeslami-Wohlert action at a pseudoscalar mass of 157(6) MeV. The result is converted non-perturbatively to the RI'-MOM scheme and then perturbatively to the MSbar scheme at a scale mu = 2 GeV. As the quark mass is reduced we find the lattice prediction to approach the value extracted from experiments. 
Gunnar S. Bali, Sara Collins, Mridupawan Deka, Benjamin Glaessle,   Meinulf Gockeler, Johannes Najjar, Andrea Nobile, Dirk P...
hep-lat hep-ph