Bimetric gravity and two-component fluid in the AdS/CFT correspondence
  We study bimetric gravity through the context of the AdS/CFT correspondence, especially, in the first order hdrodynamic limit. If we put pure general relativity as a bulk field, the boundary field theory is interpreted as fluid of the N = 4 supersymmetric Yang-Mills plasma. The transport coefficients of this plasma are computed via the AdS/CFT correspondence. Then, we prepare a pair of gravitational fields on the bulk side and let them interact. We expect that two-component fluid emerge on the CFT boundary side because the number of metrics becomes double. However, the situation is rather complicated. The interaction generates a massive graviton. This massive mode leads to the extra divergences which are absent in the case of general relativity. Our first investigation is how to cancel these divergences. After that, we see the emergence of two-component fluid and calculate their pressure and sheer viscosity. The interaction makes two kinds of fluid mixed and the sheer viscosity obtain slight correction dependent on the mass of a graviton. 
Kouichi Nomura
hep-th gr-qc