Constraints on Wrapped DBI Inflation in a Warped Throat

TL;DR

This paper derives constraints on warped throat parameters for DBI inflation, showing that a high background charge is needed for compatibility with WMAP3 data, largely independent of the inflaton potential details.

Contribution

It provides new bounds on the background charge and tensor-to-scalar ratio in warped throat DBI inflation models, applicable broadly across different throat geometries.

Findings

High background charge is required for observational consistency.

Most results are insensitive to inflaton potential details.

Constraints are applicable to generic warped throat scenarios.

Abstract

We derive constraints on the tensor to scalar ratio and on the background charge of the warped throat for DBI inflation driven by D5- and D7-branes wrapped over cycles of the throat. It is shown that the background charge well beyond the known maximal value is required in most cases for DBI inflation to generate cosmological observables compatible with the WMAP3 data. Most of the results derived in this paper are insensitive to the details of the inflaton potential, and could be applied to generic warped throats.