Stability of de Sitter spacetime against infrared quantum scalar field fluctuations

Understand

We study the backreaction of superhorizon fluctuations of a light quantum scalar field on a classical de Sitter geometry by means of the Wilsonian renormalisation group.

• This allows us to treat the gravitationally amplified fluctuations in a nonperturbative manner and to analytically follow the induced renormalisation flow of the spacetime curvature as long wavelength modes are progressively integrated out.
• Unbounded loop corrections in the deep infrared are eventually screened by nonperturbative effects which stabilise the geometry.