Adding matter to Poincare invariant branes - art. no. 086006

A solution to the cosmological constant problem has been proposed in which our universe is a 3-brane in a 5-dimensional spacetime. With a bulk scalar, the field equations admit a Poincare invariant brane solution regardless o f the value of the cosmological constant (tension) on the brane. However, t he solution does not include matter in the brane. We find new exact static solutions with matter density and pressure in the brane. We study small per turbations about these solutions. None seem consistent with observational c osmology. As a by-product we find a class of new matterless static solution s and a non-static solution which, curiously, requires the string value for the dilaton coupling.