Non-Gaussian inflationary shapes in G3G^3 theories beyond Horndeski

Jul 27, 2014
17 pages
Published in:
  • JCAP 10 (2014) 037
  • Published: Oct 15, 2014
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Abstract: (IOP)
We consider the possible signatures of a recently introduced class of healthy theories beyond Horndeski models on higher-order correlators of the inflationary curvature fluctuation. Despite the apparent large number and complexity of the cubic interactions, we show that the leading-order bispectrum generated by the Generalized Horndeski (also called G(3)) interactions can be reduced to a linear combination of two well known k-inflationary shapes. We conjecture that said behavior is not an accident of the cubic order but a consequence dictated by the requirements on the absence of Ostrogradski instability, the general covariance and the linear dispersion relation in these theories.
Note:
  • 17 pages. Analysis expanded and some references added
  • modified gravity
  • inflation
  • non-gaussianity
  • cosmological perturbation theory
  • inflation: correlation function
  • inflation: non-Gaussianity
  • correlation function: higher-order
  • dispersion relation: linear
  • curvature: fluctuation
  • gravitation: model
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