DBI Inflation using a One-Parameter Family of Throat Geometries

TL;DR

This paper explores how different throat geometries in DBI inflation models affect cosmological signatures, showing that variations can lead to observable differences in spectral indices and non-Gaussianity.

Contribution

It introduces a one-parameter family of throat geometries using the BGMPZ solution to analyze their impact on inflationary observables.

Findings

Warp factor variations significantly alter spectral indices.

Different geometries increase non-Gaussianity.

Models can be distinguished by current and future experiments.

Abstract

We demonstrate the possibility of examining cosmological signatures in the DBI inflation setup using the BGMPZ solution, a one-parameter family of geometries for the warped throat which interpolate between the Maldacena-Nunez and Klebanov-Strassler solutions. The warp factor is determined numerically and subsequently used to calculate cosmological observables including the scalar and tensor spectral indices, for a sample point in the parameter space. As one moves away from the KS solution for the throat the warp factor is qualitatively different, which leads to a significant change for the observables, but also generically increases the non-Gaussianity of the models. We argue that the different models can potentially be differentiated by current and future experiments.