Relativistic field equations from higher-order polarizations of the   Poincar\'e group
  The theory of free relativistic fields is shown to arise in a unified manner from higher-order, configuration-space, irreducible representations of the Poincar\'e group. A de Sitter subalgebra, in the massive case, and a Poincar\'e subalgebra, in the massless case, of the enveloping algebra of the Poincar\'e group are the suitable higher-order polarizations. In particular, a simple group-theoretic derivation of the Dirac equation is given. 
Miguel Navarro (Granada U., Madrid, IMAFF), Manuel Calixto (Granada   U.) and V\'ictor Aldaya (Granada U., Valencia U.)