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arXiv · 1407.7280

Non-Gaussian inflationary shapes in $G^3$ theories beyond Horndeski

Matteo Fasiello·Sébastien Renaux-Petel
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Abstract

We consider the possible signatures of a recently introduced class of healthy theories beyond Horndeski models on higher-order correlators of the inflationary curvature fluctuation. Despite the apparent large number and complexity of the cubic interactions, we show that the leading-order bispectrum generated by the Generalized Horndeski (also called $G^3$) interactions can be reduced to a linear combination of two well known $k$-inflationary shapes. We conjecture that said behavior is not an accident of the cubic order but a consequence dictated by the requirements on the absence of Ostrogradski instability, the general covariance and the linear dispersion relation in these theories.

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Matteo Fasiello, Sébastien Renaux-Petel. 2014-09-03. Non-Gaussian inflationary shapes in $G^3$ theories beyond Horndeski. https://doi.org/10.1088/1475-7516%2F2014%2F10%2F037

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