Multifield DBI Inflation and Non-Gaussianities

TL;DR

This paper investigates multifield DBI inflation, demonstrating that its trajectories resemble slow roll inflation and analyzing how higher derivative terms affect perturbations and non-Gaussianities, revealing distinctive bispectrum features.

Contribution

It provides a detailed analysis of multifield DBI inflation trajectories and their perturbation spectra, highlighting the effects of higher derivative terms on non-Gaussianities.

Findings

Trajectories are similar to slow roll inflation.

Higher derivative terms suppress isocurvature contributions.

Distinctive features in the bispectrum from isocurvature perturbations.

Abstract

We analyze the trajectories for multifield DBI inflation, which can arise in brane inflation models, and show that the trajectories are the same as in typical slow roll inflation. We calculate the power spectrum and find that the higher derivative terms of the DBI action lead to a suppression of the contribution from the isocurvature perturbations. We also calculate the bispectrum generated by the isocurvature perturbation, and find that it leads to distinctive features.