A Delicate Universe

TL;DR

This paper explores the feasibility of explicit warped D-brane inflation models within string theory, focusing on how D7-branes influence the inflaton potential and the delicate conditions needed for slow roll inflation.

Contribution

It provides a detailed analysis of the potential modifications due to D7-branes and constructs a specific example demonstrating the fine-tuning required for inflation in this context.

Findings

Inflation can occur near an inflection point with fine-tuning.

The inflaton potential is highly sensitive to the shape of the potential.

Explicit models require delicate adjustments to achieve slow roll.

Abstract

We investigate whether explicit models of warped D-brane inflation are possible in string compactifications. To this end, we study the potential for D3-brane motion in a warped conifold that includes holomorphically-embedded D7-branes involved in moduli stabilization. The presence of the D7-branes significantly modifies the inflaton potential. We construct an example based on a very simple and symmetric embedding due to Kuperstein, z_1 = constant, in which it is possible to fine-tune the potential so that slow roll inflation can occur. The resulting model is rather delicate: inflation occurs in the vicinity of an inflection point, and the cosmological predictions are extremely sensitive to the precise shape of the potential.