Platonic solids back in the sky: Icosahedral inflation

Abstract

We generalize the model of solid inflation to an anisotropic cosmic solid. Barring fine tunings, the observed isotropy of the cosmological background and of the scalar two-point function isolate the icosahedral group as the only possible symmetry group of such a solid. In such a case, higher-point correlation functions---starting with the three-point one---are naturally maximally anisotropic, which makes the standard detection strategies highly inefficient and calls for a dedicated analysis of CMB data. The tensor two-point function can also be highly anisotropic, but only in the presence of sizable higher-derivative couplings.

20 pages

References in corpus (2)

• The Effective Field Theory of Inflation
• The expected anisotropy in solid inflation

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• Scalar-tensor mixing from icosahedral inflation
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