Spectra, vacua and the unitarity of Lovelock gravity in D-dimensional AdS spacetimes

Understand

We explicitly confirm the expectation that generic Lovelock gravity in D dimensions has a unitary massless spin-2 excitation around any one of its constant curvature vacua just like the cosmological Einstein gravity.

• The propagator of the theory reduces to that of Einstein's gravity, but scattering amplitudes must be computed with an effective Newton's constant which we provide.
• Tree-level unitarity imposes a single constraint on the parameters of the theory yielding a wide range of unitary region.
• As an example, we explicitly work out the details of the cubic Lovelock theory.