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arXiv · 1409.2949

Curvaton with Nonminimal Derivative Coupling to Gravity II: Full Perturbation Analysis

Kaixi Feng·Taotao Qiu
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Abstract

In our previous work \cite{Feng:2013pba}, we have shown a curvaton model where the curvaton has a nonminimal derivative coupling to gravity. Such a coupling could bring us scale-invariance of the perturbations for wide range constant values of the equation-of-state of the cosmic background at the early time. In this paper, we continue our study by fully analyzing its perturbations up to the third order. Apart from the usual 2-point correlation function that has already been calculated in \cite{Feng:2013pba}, we have also taken into account the 3-point correlation functions including pure scalar part, pure tensor part, as well as the cross-correlations between scalar and tensor perturbation modes. We find that for pure scalar part, the 3-point correlation functions can generate non-Gaussianities that fits the PLANCK data very well. For pure tensor and mixed parts, the shape functions have peaks at squeezed and equilateral limits respectively, responsible for sizable $f_{NL}^{sqz}$ and $f_{NL}^{eql}$, which could be tested by the future observatioanl data.

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Kaixi Feng, Taotao Qiu. 2014-12-10. Curvaton with Nonminimal Derivative Coupling to Gravity II: Full Perturbation Analysis. https://doi.org/10.1103/physrevd.90.123508

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