Universal terms of the entanglement entropy in a static closed universe

TL;DR

This paper analytically and numerically investigates universal logarithmic corrections to entanglement entropy in a static closed universe, revealing geometry-dependent coefficients that are regulator-independent.

Contribution

It provides the first perturbative calculation and numerical verification of two universal coefficients of entanglement entropy in a curved static universe.

Findings

First coefficient is a known correction independent of geometry.

Second coefficient depends on intrinsic and extrinsic geometries.

Numerical results agree with analytical calculations within high accuracy.

Abstract

Subdominant contributions to the entanglement entropy of quantum fields include logarithmic corrections to the area law characterized by universal coefficients that are independent of the ultraviolet regulator and capture detailed information on the geometry around the entangling surface. We determine two universal coefficients of the entanglement entropy for a massive scalar field in a static closed universe $\mathbb{R} \times \mathbb{S}^3$ perturbatively and verify the results numerically. The first coefficient describes a well known generic correction to the area law independent of the geometry of the entangling surface and background. The second coefficient describes a curvature-dependent universal term with a nontrivial dependence on the intrinsic and extrinsic geometries of the entangling surface and curvature of the background. The numerical calculations confirm the analytical results to a high accuracy. The first and second universal coefficients are determined numerically with a relative error with respect to the analytical values of the orders $10^{-4}$ and $10^{-2}$, respectively.