Conditional escape of gravitons from the brane
  In this paper we consider a cosmological Friedmann Robertson Walker brane world imbedded in a 5-dimensional anti-de Sitter Schwarzschild bulk. We show, using potential diagrams, that for an anti-de Sitter bulk the null geodesics never return to the brane. Null geodesics do however return for k=+1 when we include the Schwarzschild like mass and the condition of return is obtained from the corresponding effective potential. We next obtain the condition for a gravitational signal to be emitted from a FRW brane with isotropically distributed matter. We use these results to investigate the conditions under which shortcuts through the bulk are possible. 
Jannie A.Leach and William M. Lesame