Thick branes and Gauss-Bonnet self-interactions

Thick branes obtained from a bulk action containing Gauss-Bonnet self-interactions are analyzed in light of the localization properties of the various modes of the geometry. The entangled system describing the localization of the tensor, vector, and scalar fluctuation is decoupled in terms of variables invariant for infinitesimal coordinate trans formations. The dynamics of the various zero modes is discussed and solved in general terms. Provided the four-dimensional Planck mass is finite and provided the geometry is everywhere regular, it is shown that the vector and scalar zero modes are not localized. The tensor zero mode is localized leading to four-dimensional gravity. The general formalism is illustrated through specific analytical examples.