Title: The Ostrogradsky instability can be overcome by quantum physics
Speaker: John F. Donoghue (University of Massachusetts Amherst)
Abstract: This work is motivated by the theory of quadratic gravity, which is a renormalizeable UV complete theory of gravity. This theory involves higher derivatives in the action. In general for theories with higher time derivatives, the Hamiltonian analysis of Ostrogradsky predicts an instability. However, this Hamiltonian treatment does not correspond the way that these theories are treated in quantum field theory, and the instability may be avoided in at least some cases. I will describe a very simple model which illustrates these features. I then go on to discuss other aspects of such higher derivative theories, including causality and unitarity.
