On the quantum field theory of the gravitational interactions

Understand

We study the main options for a unitary and renormalizable, local quantum field theory of the gravitational interactions.

• The first model is a Lee-Wick superrenormalizable higher-derivative gravity, formulated as a nonanalytically Wick rotated Euclidean theory.
• We show that, under certain conditions, the $S$ matrix is unitary when the cosmological constant vanishes.
• The model is the simplest of its class.