I will discuss the possibility of realizing composite massless spin-2 states in four dimensions by means of a holographic dual theory in five-dimensional asymptotically AdS spacetime. The bulk theory consists of Einstein gravity plus a scalar field, whose potential drives the spacetime away from the AdS solution, and generically causes it to end in a singularity. The particle spectrum of the dual 4D theory is encoded in the spectrum of fluctuations around the classical 5D solution. Under certain conditions, the 4D massless spectrum consists of a single spin-2 mode, with no additional light scalars or vectors. As the 5D profile of these modes is peaked away from the AdS boundary, they are to be considered as composite states under the holographic duality.

Polytechnique