Manifestly Covariant Canonical Formalism of Quadratic Gravity

by Ichiro Oda (Ryukyus University, Okinawa)

Thursday 12 Jun 2025, 14:30 → 16:30 Europe/Rome

he construction of a quantum field theory (QFT) of gravity  in four dimensions is one of the most important and fascinating problems in modern particle physics. In recent years, we watch a revival of  a considerable interest in the perturbatively renormalizable quantum gravity, which is nowadays called "quadratic gravity", where quadratic curvature terms are added to the Einstein-Hilbert action. This revival mainly comes from the following two reasons: First, quadratic gravity is a renormalizable theory so it not only provides us with an example of an ultraviolet (UV)-complete theory but also is highly predictive in the sense that the results obtained from this theory  can be tested in the near future.  Second, many new ideas have been recently addressed to solve an infamous problem in quadratic gravity, which is the unitarity violation owing to the existence of physical massive ghost.
These new ideas are mainly based on Feynman's path integral formalism. In this seminar, as an alternative formalism of QFT, we will present the manifestly covariant canonical formulation of
quadratic gravity in the covariant de Donder gauge on the basis of the BRST approach. Moreover, a new idea for solving the problem of the massive ghost will be advocated.