One conjecture and two observations on de Sitter space

TL;DR

This paper proposes a new perspective on the thermodynamics of de Sitter space, suggesting a non-CFT dual theory and exploring phase transitions near the Nariai limit.

Contribution

It introduces the idea that the Nariai black hole state is the ground state of de Sitter gravity and explores the nature of the dual field theory in different regimes.

Findings

Dual theory cannot be a fixed-dimension CFT.

Near Nariai limit, dual is an effective 1+1 CFT.

Beyond de Sitter limit, high-temperature phase described by a lower-dimensional CFT.

Abstract

We propose that the state represented by the Nariai black hole inside de Sitter space is the ground state of the de Sitter gravity, while the pure de Sitter space is the maximal energy state. With this point of view, we investigate thermodynamics of de Sitter space, we find that if there is a dual field theory, this theory can not be a CFT in a fixed dimension. Near the Nariai limit, we conjecture that the dual theory is effectively an 1+1 CFT living on the radial segment connecting the cosmic horizon and the black hole horizon. If we go beyond the de Sitter limit, the "imaginary" high temperature phase can be described by a CFT with one dimension lower than the spacetime dimension. Below the de Sitter limit, we are approaching a phase similar to the Hagedorn phase in 2+1 dimensions, the latter is also a maximal energy phase if we hold the volume fixed.