Puncture of gravitating domain walls

TL;DR

This paper analyzes the semi-classical decay of gravitating vacuum domain walls through puncture processes, calculating instanton rates and exploring implications for universe expansion and brane-world scenarios.

Contribution

It introduces a detailed calculation of decay rates for punctured domain walls and examines their impact on cosmological expansion and stability in brane-world models.

Findings

Puncture processes lead to exponential growth of holes in the wall.

A single puncture does not fully thermalize the wall, leaving a matter shell.

At least four string loops are needed to completely annihilate the wall.

Abstract

We investigate the semi-classical instability of vacuum domain walls to processes where the domain walls decay by the formation of closed string loop boundaries on their worldvolumes. Intuitively, a wall which is initially spherical may `pop', so that a hole corresponding to a string boundary component on the wall, may form. We find instantons, and calculate the rates, for such processes. We show that after puncture, the hole grows exponentially at the same rate that the wall expands. It follows that the wall is never completely thermalized by a single expanding hole; at arbitrarily late times there is still a large, thin shell of matter which may drive an exponential expansion of the universe. We also study the situation where the wall is subjected to multiple punctures. We find that in order to completely annihilate the wall by this process, at least four string loops must be nucleated. We argue that this process may be relevant in certain brane-world scenarios, where the universe itself is a domain wall.