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arXiv · 1507.04344

Reinterpretation of the Starobinsky model

Takehiko Asaka·Satoshi Iso·Hikaru Kawai·Kazunori Kohri·Toshifumi Noumi·Takahiro Terada
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Abstract

The Starobinsky model of inflation, consistent with Planck 2015, has a peculiar form of the action, which contains the leading Einstein term $R$, the $R^2$ term with a huge coefficient, and negligible higher-order terms. We propose an explanation of this form based on compactification of extra dimensions. Once tuning of order $10^{-4}$ is accepted to suppress the linear term $R$, we no longer have to suppress higher-oder terms, which give nontrivial corrections to the Starobinsky model. We show our predictions of the spectral index, its runnings, and the tensor-to-scalar ratio. Finally, we discuss a possibility that quantum gravity may appear at the scale $\Lambda \gtrsim 5 \times 10^{15}$ GeV.

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Takehiko Asaka, Satoshi Iso, Hikaru Kawai, Kazunori Kohri, Toshifumi Noumi, Takahiro Terada. 2015-07-15. Reinterpretation of the Starobinsky model. https://doi.org/10.1093/ptep/ptw161

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