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arXiv · 0712.2345

Inflationary NonGaussianity from Thermal Fluctuations

Bin Chen·Yi Wang·Wei Xue
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Abstract

We calculate the contribution of the fluctuations with the thermal origin to the inflationary nonGaussianity. We find that even a small component of radiation can lead to a large nonGaussianity. We show that this thermal nonGaussianity always has positive $f_{\rm NL}$. We illustrate our result in the chain inflation model and the very weakly dissipative warm inflation model. We show that $f_{NL}\sim {\cal O}(1)$ is general in such models. If we allow modified equation of state, or some decoupling effects, the large thermal nonGaussianity of order $f_{\rm NL}>5$ or even $f_{\rm NL}\sim 100$ can be produced. We also show that the power spectrum of chain inflation should have a thermal origin. In the Appendix A, we made a clarification on the different conventions used in the literature related to the calculation of $f_{\rm NL}$.

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Bin Chen, Yi Wang, Wei Xue. 2007-12-18. Inflationary NonGaussianity from Thermal Fluctuations. https://doi.org/10.1088/1475-7516%2F2008%2F05%2F014

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