Massless Particles, Conformal Group and De Sitter Universe

@article{Angelopoulos1981MasslessPC,
  title={Massless Particles, Conformal Group and De Sitter Universe},
  author={E. Angelopoulos and M. Flato and C. Fr{\o}nsdal and D. Sternheimer},
  journal={Physical Review D},
  year={1981},
  volume={23},
  pages={1278-1289}
}
We first review a recent result on the uniqueness of the extension to the conformal group of massless representations of the Poincare group. By restricting these representations to SO(3,2) we obtain a unique definition of massless particles in de Sitter space. This definition is compared with the concept of masslessness that arises from considerations of gauge invariance. Next, we recall the startling fact that the direct product of two Dirac singleton representations of SO(3,2) decomposes into… Expand
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