Speaker
Description
Adding terms quadratic in the curvature to the Einstein-Hilbert action renders gravity renormalizable. This property is preserved in the presence of the most general renormalizable couplings with (and of) a generic quantum field theory. The price to pay is a massive ghost, which is due to the higher derivatives that the terms quadratic in the curvature imply. This quadratic gravity scenario will be summarized including recent progress on the related stability and unitarity problems of higher derivative theories. The theory can be extrapolated up to infinite energy through the renormalization group if all matter couplings flow to a fixed point (either trivial or interacting). In this case the theory can approach conformal gravity at infinite energy. A way to address the hierarchy problem within this scenario will also be discussed.
