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Non-Gaussianity in braneworld and tachyon inflation

Gianluca Calcagni
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Abstract

We calculate the bispectrum of single-field braneworld inflation, triggered by either an ordinary scalar field or a cosmological tachyon, by means of a gradient expansion of large-scale non-linear perturbations coupled to stochastic dynamics. The resulting effect is identical to that for single-field 4D standard inflation, the non-linearity parameter being proportional to the scalar spectral index in the limit of collapsing momentum. If the slow-roll approximation is assumed, braneworld and tachyon non-Gaussianities are subdominant with respect to the post-inflationary contribution. However, bulk physics may considerably strengthen the non-linear signatures. These features do not change significantly when considered in a non-commutative framework.

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Gianluca Calcagni. 2005-10-19. Non-Gaussianity in braneworld and tachyon inflation. https://doi.org/10.1088/1475-7516%2F2005%2F10%2F009

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