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arXiv · 1207.4410

Non-Gaussianities in multi-field DBI inflation with a waterfall phase transition

Taichi Kidani·Kazuya Koyama·Shuntaro Mizuno
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Abstract

We study multi-field DBI inflation models with a waterfall phase transition. This transition happens for a D3 brane moving in the warped conifold if there is an instability along angular directions. The transition converts the angular perturbations into the curvature perturbation. Thanks to this conversion, multi-field models can evade the stringent constraints that strongly disfavour single field ultra-violet DBI inflation models in string theory. We explicitly demonstrate that our model satisfies current observational constraints on the spectral index and equilateral non-Gaussianity as well as the bound on the tensor to scalar ratio imposed in string theory models. In addition we show that large local type non-Gaussianity is generated together with equilateral non-Gaussianity in this model.

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Taichi Kidani, Kazuya Koyama, Shuntaro Mizuno. 2012-11-28. Non-Gaussianities in multi-field DBI inflation with a waterfall phase transition. https://doi.org/10.1103/physrevd.86.083503

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