DBI N-flation

TL;DR

This paper explores DBI inflation with multiple branes, showing its equivalence to a single wrapped D5-brane, analyzing non-Gaussianities, and proposing a novel inflation mechanism via representation cascade.

Contribution

It introduces a framework for multi-brane DBI inflation, incorporates 1/N corrections, and proposes a new inflationary mechanism based on representation transitions.

Findings

Non-Gaussianity amplitude is bounded in constant warping models.

Large positive non-Gaussianities are typical in AdS backgrounds.

The representation cascade mechanism can drive inflation.

Abstract

We investigate DBI inflation using $N$ multiple branes and show how the configuration is equivalent to a single wrapped $D5$-brane with flux. We then show how 1/N corrections can be implemented, and we examine the sound speed and levels of non-Gaussianities in two distinct cases. For models with constant warping we find that the non-Gaussian amplitude is bounded from above (as a function of $\gamma$). For $AdS$ backgrounds we find that the signature is generally large and positive, although is no longer globally defined over the full phase space. We then investigate an inflationary mechanism using a representation cascade, whereby the transition from a reducible representation to the irrep drives inflation.