Towards a warped inflationary brane scanning

TL;DR

This paper systematically compares warped brane inflation models with observations, explicitly constructs the inflaton potential, and explores how bulk effects influence the model's observational viability, highlighting the need for fine tuning.

Contribution

It provides a detailed construction of the inflaton potential in warped deformed conifold scenarios and analyzes the impact of bulk effects on inflationary predictions.

Findings

Bulk effects can spoil observational predictions without fine tuning.

Degenerate parameter sets can produce consistent predictions without bulk effects.

Suppression of bulk effects is necessary for model viability.

Abstract

We present a detailed systematics for comparing warped brane inflation with the observations, incorporating the effects of both moduli stabilization and ultraviolet bulk physics. We explicitly construct an example of the inflaton potential governing the motion of a mobile D3 brane in the entire warped deformed conifold. This allows us to precisely identify the corresponding scales of the cosmic microwave background. The effects due to bulk fluxes or localized sources are parametrized using gauge/string duality. We next perform some sample scannings to explore the parameter space of the complete potential, and first demonstrate that without the bulk effects there can be large degenerate sets of parameters with observationally consistent predictions. When the bulk perturbations are included, however, the observational predictions are generally spoiled. For them to remain consistent, the magnitudes of the bulk effects need to be highly suppressed via fine tuning.