Entanglement and factorization in axion-de Sitter universes

Abstract

We study extremal codimension-two areas and late-time bulk correlators between a pair of asymptotically de Sitter space universes connected through an Euclidean axion wormhole, in arbitrary dimensions. Assuming the validity of the de Sitter (dS)/conformal field theory (CFT) correspondence, we describe factorized Hilbert spaces for the putative boundary theories at $\mathcal{I}^+$ in each of the universes based on the asymptotically dS isometries. This allow us to we interpret the extremal areas as complex-valued holographic entanglement entropy between the microscopic duals. Later, we evaluate two-point correlation functions for heavy particles detected near $\mathcal{I}^+$. The Euclidean wormhole saddle point is responsible for finiteness of the correlators. The results are compatible with the boundary dual being non-unitary and having a large Hilbert space dimension. At last, we dimensionally reduce these geometries in terms of dilaton-gravity theory with conformally coupled matter.