Constraints on the brane and bulk ideal fluid in Randall-Sundrum cosmologies - art. no. 044017

We investigate constraints for including bulk and brane matter in the Randa ll-Sundrum model. In static configurations with two zero thickness branes, we find that no realistic brane matter is possible. We also consider the po ssibility that the radion has stabilized by dissipating its energy into the bulk in the form of some unspecified matter, and find the Randall-Sundrum cosmological solutions in the presence of bulk ideal fluid. We discover tha t the metric is necessarily in a static configuration. We also discover tha t there is only one allowed equation of state for the bulk fluid, p = rho, corresponding to the stiff ideal fluid. We find the corresponding brane cos mologies and compare them with the Friedmann-Robertson-Walker model.