Consistent Massive Colored Gravitons
  A short review of the problems with the action for massive gravitons is presented. We show that consistency problems could be resolved by employing spontaneous symmetry breaking to give masses to gravitons. The idea is then generalized by enlarging the SL(2,C) symmetry to $SL(2N,C)x SL(2N,C) which is broken to $SL(2,C) spontaneously through a non-linear realization. The requirement that the space-time metric is generated dynamically forces the action constructed to be a four-form. It is shown that the spectrum of this model consists of two sets of massive matrix gravitons in the adjoint representation of SU(N) and thus are colored, as well as two singlets, one describing a massive graviton, the other being the familiar massless graviton. 
Ali H. Chamseddine