D-brane Potentials in the Warped Resolved Conifold and Natural Inflation

TL;DR

This paper constructs a string theory model of Natural Inflation using D-branes in a warped resolved conifold, achieving a Planckian decay constant while maintaining control over backreaction effects.

Contribution

It provides an exact solution for D-brane potentials in the warped resolved conifold, enabling a Natural Inflation model with a large decay constant from string theory.

Findings

Achieved a Planckian decay constant in a string inflation model.

Exact solutions for D-brane potentials on the resolved conifold.

Controlled backreaction with small wrapping parameters.

Abstract

In this paper we obtain a model of Natural Inflation from string theory with a Planckian decay constant. We investigate D-brane dynamics in the background of the warped resolved conifold (WRC) throat approximation of Type IIB string compactifications on Calabi-Yau manifolds. When we glue the throat to a compact bulk Calabi-Yau, we generate a D-brane potential which is a solution to the Laplace equation on the resolved conifold. We can exactly solve this equation, including dependence on the angular coordinates. The solutions are valid down to the tip of the resolved conifold, which is not the case for the more commonly used deformed conifold. This allows us to exploit the effect of the warping, which is strongest at the tip. We inflate near the tip using an angular coordinate of a D5-brane in the WRC which has a discrete shift symmetry, and feels a cosine potential, giving us a model of Natural Inflation, from which it is possible to get a Planckian decay constant whilst maintaining control over the backreaction. This is because the decay constant for a wrapped brane contains powers of the warp factor, and so can be made large, while the wrapping parameter can be kept small enough so that backreaction is under control.