Orbital Angular Momentum in Scalar Diquark Model and QED
  We compare the orbital angular momentum of the 'quark' in the scalar diquark model as well as that of the electron in QED (to order {\alpha}) obtained from the Jaffe-Manohar de- composition to that obtained from the Ji relation. We estimate the importance of the vector potential in the definition of orbital angular momentum. 
Hikmat BC and Matthias Burkardt
hep-ph