Speaker
Description
We will show how to construct the proper low-energy limit of QFT in curved spacetime from a canonically quantized gravity-matter system, discussing four emerging points of previous literature. To address the related shortcomings, we will consider the gravitational sector as composed of a classical background (i.e. a vacuum Bianchi I universe) and quantum fluctuations on top (gravitons) regarded as “slow” quantum components in a Born-Oppenheimer approximation, while the matter scalar field will have a “fast” quantum character. Via a WKB expansion of the full system, the quantum matter dynamics will recover a functional Schrödinger form after averaging over quantum gravitational effects, thanks to a gauge condition imposed on the gravitons’ wave functional, which is equivalent to the gravitational Wheeler-DeWitt constraint implemented a priori in previous approaches.
