Parton distribution functions from QCD in Euclidean space

Parton distribution functions are essential inputs in extracting information from high-energy physics emperiments. However the computation for these distribution functions is a major challenge in Lattice QCD. In recent years, novel approaches have been advocated for such calculations.

  • The method of the valence heavy quark
  • This is based on the proposal by Detmold and Lin. Through the introduction of a pure valence heavy quark, one can use the heavy mass to perform the OPE in Euclidean space and obtain high moments of the parton distribution functions.

  • The method of the position-space operator product expansion
  • This was advocated by Braun and Mueller. Using the short distance in Euclidean space in the OPE, one can extract moments of the parton distribution functions.

  • The method of the quasi parton distribution functions
  • This approach employs the large-momentum effective theory and was first studied by Ji.

  • Other approaches
  • These include the QCDSF method, and the proposal from the Kentucky group.