Quantum Gravity, de Sitter Space, and Normalizability

TL;DR

This paper resolves the normalizability issues of the Lorentzian Chern-Simons-Kodama state in quantum gravity with positive cosmological constant, establishing it as a viable de Sitter vacuum state.

Contribution

It introduces a nonperturbative inner product and phase space rotation to demonstrate the perturbative normalizability of the CSK state for all cosmological constants.

Findings

CSK state is perturbatively normalizable for super-Planckian $\

A phase space rotation renders the full state normalizable for all $\

First concrete realization of a CPT-breaking, normalizable quantum gravity vacuum in de Sitter space.

Abstract

We propose a resolution to the longstanding problem of perturbative normalizability in canonical quantum gravity of the Lorentzian Chern-Simons-Kodama (CSK) state with a positive cosmological constant in four dimensions. While the CSK state is an exact solution to the Hamiltonian constraint in the self-dual formulation and semiclassically describes de Sitter spacetime, its physical viability has been questioned due to apparent nonnormalizability and CPT asymmetry. Starting from a nonperturbative holomorphic inner product derived from the reality conditions of the self-dual Ashtekar variables, we show that the linearization, in terms of gravitons, of the CSK state is perturbatively normalizable for super-Planckian cosmological constant. Furthermore, we demonstrate that a rotation in phase space, a generalization of Thiemann's complexifier, can render the full perturbative state normalizable for all $\Lambda$ by analytically continuing the non-convergent modes in phase space. This provides the first concrete realization of a CPT-breaking, yet normalizable, gravitational vacuum state rooted in a nonperturbative quantum gravity framework. Our results establish the CSK state-long thought formal-as a viable candidate for the ground state of quantum gravity in de Sitter space.