Dynamical instabilities of the Randall-Sundrum model - art. no. 063504

We derive dynamical equations to describe a single 3-brane containing fluid matter and a scalar field coupling to the dilaton and the gravitational fi eld in a five-dimensional bulk. First. we show that a scalar field or an ar bitrary fluid on the brane cannot evolve to cancel the cosmological constan t in the bulk. Then we show that the Randall-Sundrum model is unstable unde r small deviations from the fine-tuning between the brane tension and the b ulk cosmological constant and even under homogeneous gravitational perturba tions. Implications for brane world cosmologies are discussed.