  This work applies lattice QCD to compute quark momentum distributions in the
nucleon. We explore a novel approach based on non-local operators in order to
analyze transverse momentum dependent parton distribution functions, which
encode information about the intrinsic motion of quarks inside the nucleon. Our
calculations are based on MILC gauge configurations and domain wall fermion
propagators from LHPC. One interesting observation is that the transverse
momentum dependent density of polarized quarks in a polarized nucleon is
visibly deformed. Moreover, we can test the assumption that longitudinal and
transverse momentum dependence factorize within a certain kinematical region. A
more elaborate operator geometry is required to enable a quantitative
comparison to azimuthal asymmetries observable in experiments such as
semi-inclusive deeply inelastic scattering, and to study time-reversal odd
distributions such as the Sivers function. First steps in this direction are
encouraging.
