Brane-World Inflation and the Transition to Standard Cosmology

TL;DR

This paper develops a framework for brane-world inflation in a five-dimensional model, analyzing background solutions, slow-roll conditions, and transitions to flat vacuum states, with specific models demonstrating successful transitions.

Contribution

It introduces a classification of background solutions and analyzes conditions for transitioning from inflation to flat vacuum in brane-world scenarios, including explicit models.

Findings

Solutions with positive bulk and brane potentials are non-separating and have a non-static orbifold.

Transition to flat vacuum during inflation is prevented by rapid orbifold expansion in certain models.

Explicit models with negative boundary potential achieve successful transition to flat vacuum.

Abstract

In the context of a five-dimensional brane-world model motivated from heterotic M-theory, we develop a framework for potential-driven brane-world inflation. Specifically this involves a classification of the various background solutions of (A)dS_5 type, an analysis of five-dimensional slow-roll conditions and a study of how a transition to the flat vacuum state can be realized. It is shown that solutions with bulk potential and both bane potentials positive exist but are always non-separating and have a non-static orbifold. It turns out that, for this class of backgrounds, a transition to the flat vacuum state during inflation is effectively prevented by the rapidly expanding orbifold. We demonstrate that such a transition can be realized for solutions where one boundary potential is negative. For this case, we present two concrete inflationary models which exhibit the transition explicitly.