Relativistic Particles and Commutator Algebras
  We construct the vector fields associated to the space-time invariances of relativistic particle theory in flat Euclidean space-time. We show that the vector fields associated to the massive theory give rise to a differential operator realization of the Poincare algebra, while the vector fields associated to the massless theory, including the space-time supersymmetric sector, allow extensions of the conformal algebra in terms of commutators. 
W. F. Chagas-Filho