  Aspects of the QCD parton densities are briefly reviewed, drawing some
parallels to the density matrix formulation of quantum mechanics, exemplified
by Wigner functions. We elaborate on the solution of their evolution equations
using logarithmic expansions and overview their kinetic interpretation. We
illustrate how a Fokker-Planck equation can be derived using the master
formulation of the same equations and its construction in the case of the
transverse spin distributions. A simple connection of the leading order DGLAP
equation to fractional diffusion using fractional calculus is also briefly
outlined.
