Interactions of higher spin fields with gravity and branes in AdS5

We construct actions of higher spin fields interacting with gravity on AdS(5) backgrounds such that the Compton scattering amplitudes of the interaction are tree-level unitary. We then consider higher spin fields in the Randall-Sundrum scenario. There, in the fermionic case, we construct a tree-level unitary action of higher spin fields interacting with branes and linearized gravity. In the bosonic case we show that this is not in general possible. A tree-level unitary action of bosonic higher spins interacting with linearized gravity and branes is only possible in the following cases: the brane is a pure tension brane and/or Dirichlet boundary conditions are imposed thereby making bosonic higher spin fields invisible to a brane observer. We finally show that higher spins in Randall-Sundrum II braneworlds can only be produced by (decay into) gravitons at trans-Planckian scales. We end by commenting on the possible relevance of higher spin unparticles as dark matter candidates.