Zoology of graviton non-Gaussianities

We characterize graviton non-Gaussianities in models of inflation where de Sitter boosts are spontaneously broken. We discuss which of the symmetry breaking patterns studied in Nicolis et al., 2015 [1] can sustain a period of quasi de Sitter expansion, and show that the symmetry breaking pattern of Solid Inflation allows the most freedom for graviton interactions. We comment on the phenomenological consequences of some of these interactions. As a byproduct of this analysis we construct the EFT of Solid Inflation, which has all the useful features of the EFT of Inflation but for the case of broken spatial diffeomorphisms.

Automated summary

The article discusses the non-Gaussianities of gravitons in inflation models, investigates the impact of symmetry breaking patterns on quasi de Sitter expansion, and finds that the symmetry breaking pattern of Solid Inflation allows for the greatest freedom of graviton interactions, which also have phenomenological consequences.