Inflation in warped geometries

TL;DR

The paper investigates slow-roll inflation within string-theoretic warped throats by modeling the inflaton as the position of a D3-brane probe in local KKLT geometries. Using this probe dynamics framework, it computes leading corrections to the slow-roll parameter $\eta$ arising from conformal symmetry breaking in the throat, focusing on the KT throat and contrasting with the KW (AdS$_5\times T^{1,1}$) case. It finds that in the KW setup $\eta=2/3$ and, in de-Sitter deformed KT geometries, corrections can modestly reduce $\eta$ in one regime but remain of order unity in another, making $\eta\ll 1$ unlikely within this class of models. The results provide a controllable, higher-dimensional approach to evaluate $\eta$ corrections and clarify limitations on achieving sustained slow-roll inflation in throat-driven D3-brane scenarios.

Abstract

We argue that brane anti-brane inflation in string theory de-Sitter vacua of Kachru-Kallosh-Linde-Trivedi (KKLT) is captured by the dynamics of a D3-brane probe in the local KKLT model constructed in hep-th/0203041. This provides a framework to study in a controllable way corrections to the inflationary slow roll parameter ηdue to conformal symmetry breaking in a warped geometry throat. We compute the leading correction to ηfor the inflation in the Klebanov-Tseytlin throat geometry. We find that in certain regime this correction tends to decrease η. Computations in a different regime suggest however that it is unlikely that η<< 1 can be achieved with the D3-brane throat inflation.