de Sitter space as a BRST invariant coherent state of gravitons

This is the authors' abstract. We don't add key points for this paper.

The S-matrix formulation indicates that a consistent embedding of the de Sitter state in quantum gravity is possible exclusively as an excited quantum state constructed on top of a valid S-matrix vacuum such as the Minkowski vacuum. In the present paper we offer such a construction of the de Sitter state in the form of a coherent state of gravitons. Unlike previous realizations of this idea, we focus on BRST invariance as the guiding principle for physicality. In order to establish the universal rules of gauge consistency, we study the BRST-invariant construction of coherent states created by classical and quantum sources in QED and in linearized gravity. Introduction of N copies of scalar matter coupled to gravity allows us to take a special double scaling limit, a so-called species limit, in which our construction of the de Sitter state becomes exact. In this limit, the irrelevant quantum gravitational effects vanish, whereas the collective phenomena, such as Gibbons-Hawking radiation, are calculable.