We present a scalar thick brane configuration arising in a theory of 5D gravity coupled to a self—interacting scalar field. We start from a classical solution of the field equations and stud y the physics of linear fluctuations around this background which obey a Schrodinger-like equation. We further focus our attention on a special case in which it is possible to solve this equation analytically for any massive mode. This fact allows us to make a closed analysis of the massive spectrum of Kaluza-Klein (KK) excitations and to compute the corrections to Newton's law in the thin brane limit. There exist two bound states: the massless 4D graviton, which is free of tachyonic instabilities, and a massive KK excitation. There is also a continuous spectrum of massive KK modes. The mass gap existing between the massless and the excited modes is completely defined by the inverse of the brane thickness. This fact eliminates the experimentally dangerous arbitrarily light KK modes. Moreover, in this picture the solution of the mass hierarchy problem is very simple.
展开▼
