Stability of Horava-Witten Spacetimes

TL;DR

This paper demonstrates the non-perturbative stability of Horava-Witten spacetimes with branes of opposite tension by analyzing their energy and employing positive energy theorems, resolving a stability puzzle.

Contribution

It provides a detailed energy analysis and a positive energy theorem proof showing the stability of these brane configurations, accounting for bulk field dynamics.

Findings

Horava-Witten spacetimes are stable due to bulk field dynamics.

Positive energy theorem confirms non-perturbative stability.

ADM analysis illustrates stability properties explicitly.

Abstract

Horava-Witten spacetimes necessarily include two branes of opposite tension. If these branes are BPS we are led to a puzzle: a negative tension brane should be unstable as it can loose energy by expanding, whereas a BPS brane should be stable as it resides at a minimum of the energy. We provide a detailed analysis of the energy of such braneworld spacetimes in 5 dimensions. This allows us to show by a non-perturbative positive energy theorem that Horava-Witten spacetimes are stable, essentially because the dynamics of the branes is entirely accounted for by the behaviour of the bulk fields. We also perform an ADM perturbative Hamiltonian analysis at quadratic order in order to illustrate the stability properties more explicitly.