Critical Points of D-Dimensional Extended Gravities

Understand

We study the parameter space of D-dimensional cosmological Einstein gravity together with quadratic curvature terms.

• In D>4 there are in general two distinct (anti)-de Sitter vacua.
• We show that for appropriate choice of the parameters there exists a critical point for one of the vacua, for which there are only massless tensor, but neither massive tensor nor scalar, gravitons.
• At criticality, the linearized excitations have vanishing energy (as do black hole solutions).