Quantum Electrodynamics based on a Superselection Rule
  This paper analyzes, for a multi-particle system of spin-1/2 particles, the consequences of replacing the Poincare group as fundamental symmetry group by the de Sitter group SO(3,2). The flat-space approximation of the de Sitter group by the Poincare group defines a superselection rule, which correlates spin and momentum of particles. This correlation can be formulated as an interaction between two particles, which exhibits properties of the electromagnetic interaction. 
Walter Smilga