Chasing Brane Inflation in String-Theory

TL;DR

This paper explores embedding brane anti-brane inflation within a specific string theory compactification, analyzing moduli stabilization and the potential for slow-roll inflation, ultimately finding limited conditions for successful inflation.

Contribution

It provides a detailed analysis of moduli stabilization effects on brane inflation in type IIB string theory, focusing on explicit D7-brane embeddings and their impact on the inflaton potential.

Findings

Most D7-brane embeddings do not allow for fine-tuning to cancel the Coulomb attraction.

Inflation is only possible near an inflection point with a very small field range.

In general, the inflaton experiences a steep potential unsuitable for slow-roll inflation.

Abstract

We investigate the embedding of brane anti-brane inflation into a concrete type IIB string theory compactification with all moduli fixed. Specifically, we are considering a D3-brane, whose position represents the inflaton $\phi$, in a warped conifold throat in the presence of supersymmetrically embedded D7-branes and an anti D3-brane localized at the tip of the warped conifold cone. After presenting the moduli stabilization analysis for a general D7-brane embedding, we concentrate on two explicit models, the Ouyang and the Kuperstein embeddings. We analyze whether the forces, induced by moduli stabilization and acting on the D3-brane, might cancel by fine-tuning such as to leave us with the original Coulomb attraction of the anti D3-brane as the driving force for inflation. For a large class of D7-brane embeddings we obtain a negative result. Cancelations are possible only for very small intervals of $\phi$ around an inflection point but not globally. For the most part of its motion the inflaton then feels a steep, non slow-roll potential. We study the inflationary dynamics induced by this potential.