Inflation on an Open Racetrack

TL;DR

This paper develops a new D-brane inflation model incorporating multiple D7-branes and racetrack superpotentials, allowing for flexible inflationary trajectories and metastable vacua in warped throat geometries.

Contribution

It introduces an open racetrack inflation framework with multiple D7-branes, enhancing model building flexibility and stability analysis in warped compactifications.

Findings

Achieved inflationary trajectories near inflection points.

Constructed approximate Minkowski vacua before uplifting.

Demonstrated Hubble scale can exceed gravitino mass.

Abstract

We present a variant of warped D-brane inflation by incorporating multiple sets of holomorphically-embedded D7-branes involved in moduli stabilization with extent into a warped throat. The resultant D3-brane motion depends on the D7-brane configuration and the relative position of the D3-brane in these backgrounds. The non-perturbative moduli stabilization superpotential takes the racetrack form, but the additional D3-brane open string moduli dependence provides more flexibilities in model building. For concreteness, we consider D3-brane motion in the warped deformed conifold with the presence of multiple D7-branes, and derive the scalar potential valid for the entire throat. By explicit tuning of the microphysical parameters, we obtain inflationary trajectories near an inflection point for various D7-brane configurations. Moreover, the open racetrack potential admits approximate Minkowski vacua before uplifting. We demonstrate with a concrete D-brane inflation model where the Hubble scale during inflation can exceed the gravitino mass. Finally, the multiple sets of D7-branes present in this open racetrack setup also provides a mechanism to stabilize the D3-brane to metastable vacua in the intermediate region of the warped throat.