Title: Simple Models for Quadratic Gravity

Quadratic gravity is in some ways an attractive option for quantum gravity, but it also is problematic because of the presence of the unstable ghost. Here I focus on this aspect by using some theories which are simpler than the full gravitational theory, but which share the same feature. These provide interesting QFTs on their own. Besides topics such as the classical limit, positivity and causality, I will argue that the running of couplings in theories like quadratic gravity needs to be recalculated. These models are amenable to lattice methods, which may ultimately provide non-perturbative insights.