DBI Galileon in the Effective Field Theory of Inflation: Orthogonal non-Gaussianities and constraints from the Trispectrum

Abstract

Very few explicit inflationary scenarios are known to generate a large bispectrum of orthogonal shape. Dirac-Born-Infeld Galileon inflation, in which an induced gravity term is added to the DBI action, is one such model. We formulate it in the language of the effective field theory of inflation by identifying the unitary gauge operators that govern the behavior of its cosmological fluctuations. We show how to recover rather easily from this its power spectrum and bispectrum, which we calculated previously using standard cosmological perturbation theory. We push our calculations up to the determination of the fourth-order action and of the trispectrum, in which shapes absent in k-inflation arise due to the presence of higher-order derivative operators. We finally discuss the combined constraints set on this model by current observational bounds on the bispectrum and trispectrum.

17 pages + 3 appendices, 7 figures. Some clarifications and references added to match the version published in JCAP. In addition, Eq. 3.14 corrected, without consequences

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Cited by in corpus (16)

• Effective Field Theory of Cosmological Perturbations
• From Amplitudes to Contact Cosmological Correlators
• Primordial non-Gaussianities after Planck 2015: an introductory review
• Non-Gaussian inflationary shapes in $G^3$ theories beyond Horndeski
• Multi-disformal invariance of nonlinear primordial perturbations
• Symmetric Scalars
• On the Trispectrum of Galileon Inflation
• DBI Galileon inflation in the light of Planck 2015
• Galileon intermediate inflation
• The Trispectrum in the Effective Theory of Inflation with Galilean symmetry
• Constraining Galileon Inflation
• Trispectrum from Co-dimension 2(n) Galileons
• Dynamical system analysis in modified Galileon cosmology
• Halo/Galaxy Bispectrum with Equilateral-type Primordial Trispectrum
• Non-perturbative quantum Galileon in the exact renormalization group
• Instability of the cosmological DBI-Galileon in the non-relativistic limit