Theory of gravitational fluctuations in brane world models

A gauge invariant theory of gravitational fluctuations of brane-world model is presented. Without resorting to any specific gauge choice, a general method is presented in order to disentangle the fluctuations of the energy-momentum tensor of the brane from the fluctuations of the metric. The employed procedure is gauge-invariant at every step. As an application of the formalism we address the localization of metric fluctuations on scalar branes breaking spontaneously five-dimensional Poincare invariance is addressed. Assuming that the four-dimensional Planck mass is finite and that the geometry is regular, it is demonstrated that the vector and scalar fluctuations of the metric are not localized on the brane.