Domain Walls As Probes Of Gravity

TL;DR

Domain walls can serve as effective probes to distinguish between large-distance modified gravity theories and general relativity by exhibiting different gravitational effects, especially in the DGP model.

Contribution

The paper introduces the use of domain walls as probes for modified gravity, providing exact solutions and demonstrating their unique gravitational behavior compared to GR.

Findings

Low-tension domain walls are stealth in modified gravity.

Domain walls with tension below the Planck scale do not cause inflation or gravitational effects in 4D.

Exact solutions for super-massive codimension-2 branes are obtained.

Abstract

We show that domain walls are probes that enable one to distinguish large-distance modified gravity from general relativity (GR) at short distances. For example, low-tension domain walls are stealth in modified gravity, while they do produce global gravitational effects in GR. We demonstrate this by finding exact solutions for various domain walls in the DGP model. A wall with tension lower than the fundamental Planck scale does not inflate and has no gravitational effects on a 4D observer, since its 4D tension is completely screened by gravity itself. We argue that this feature remains valid in a generic class of models of infrared modified gravity. As a byproduct, we obtain exact solutions for super-massive codimension-2 branes.