Plebanski action extended to a unification of gravity and Yang-Mills theory

  title={Plebanski action extended to a unification of gravity and Yang-Mills theory},
  author={Lee Smolin},
  journal={Physical Review D},
  • L. Smolin
  • Published 6 December 2007
  • Mathematics
  • Physical Review D
We study a unification of gravity with Yang-Mills fields based on a simple extension of the Plebanski action to a Lie group G which contains the local Lorentz group. The Coleman-Mandula theorem is avoided because the dynamics has no global spacetime symmetry. This may be applied to Lisi's proposal of an E8 unified theory, giving a fully E8 invariant action. The extended form of the Plebanski action suggests a new class of spin foam models. 

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