Scalar $QCD_{4}$ on the null-plane
  We have studied the null-plane hamiltonian structure of the free Yang-Mills fields and the scalar chromodynamics ($SQCD_{4}$). Following the Dirac's procedure for constrained systems we have performed a detailed analysis of the constraint structure of both models and we give the generalized Dirac brackets for the physical variables. In the free Yang-Mills case, using the correspondence principle in the Dirac's brackets we obtain the same commutators present in the literature. 
R. Casana, B.M. Pimentel, G. E. R. Zambrano