Braneworlds, conformal fields and the gravitons

Abstract

We investigate the dynamics of Randall–Sundrum AdS5 braneworlds with five-dimensional conformal matter fields. In the scenario with a compact fifth dimension the class of conformal fields with weight −4 is associated with exact five-dimensional warped geometries which are stable under radion field perturbations and describe on the brane the dynamics of inhomogeneous dust, generalized dark radiation and homogeneous polytropic dark energy. We analyse the graviton mode fluctuations around this class of background solutions and determine their mass eigenvalues and wavefunctions from a Sturm–Liouville problem. We show that the localization of gravity is not sharp enough for large mass hierarchies to be generated. We also discuss the physical bounds imposed by experiments in particle physics, in astrophysics and in precise measurements of the low energy gravitational interaction.