New Perspectives on Moving Domain Walls in (A)dS_(5) Space

TL;DR

This paper introduces a novel moving domain wall solution in five-dimensional (A)dS space, revealing unique cosmological properties and analyzing scalar field behavior without back-reaction.

Contribution

It presents a new dynamic domain wall solution with a time-dependent bulk metric and explores scalar field normalizability in this setting.

Findings

The three-universe scale factor never vanishes.

The bulk space is confirmed to be (A)dS_5.

Scalar field normalizability and vacuum states are established.

Abstract

A new moving domain wall solution is obtained for a flat 3-universe. This consists of a bulk metric depending on both time and the extra coordinate, plus a dynamically interacting domain wall, admitted by the metric and inhabited by the three-universe. The matter contents are cosmological constants on the domain wall and the bulk. The bulk space is shown to be (A)dS_(5). A remarkable fact concerning the three-universe is that its scale factor never vanishes, even though the corresponding scale factor of the bulk metric vanishes. The inclusion of a bulk scalar field is discussed, neglecting back-reaction. Its normalizability and the existence of a positive frequency or adiabatic bulk vacuum are shown.