Decoding the bispectrum of single-field inflation
arXiv:1108.3839 · doi:10.1088/1475-7516/2011/10/027
Abstract
Galileon fields arise naturally from the decoupling limit of massive gravities, and possess special self-interactions which are protected by a spacetime generalization of Galilean symmetry. We briefly revisit the inflationary phenomenology of Galileon theories. Working from recent computations of the fluctuation Lagrangian to cubic order in the most general model with second-order equations of motion, we show that a distinct shape is present but with suppressed amplitude. A similar shape has been found in other higher-derivative models. It may be visible in a theory tuned to suppress the leading-order shapes, or if the overall bispectrum has large amplitude. Using a partial-wave expansion of the bispectrum, we suggest a possible origin for the frequent appearance of this shape. It follows that models with very disparate microphysics can produce very similar bispectra. We argue that it may be more profitable to distinguish these models by searching for relations between the amplitudes of these common shapes. We illustrate this method using the example of DBI and k-inflation.
v1: 25 pages, including tables, an appendix and references. v2: minor clarifications about the lowest-order consistency relations; matches version published in JCAP
References in corpus (26)
- Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
- Resummation of Massive Gravity
- Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
- The Effective Field Theory of Inflation
- Covariant Galileon
- Observational Signatures and Non-Gaussianities of General Single Field Inflation
- Generalized Galileons: All scalar models whose curved background extensions maintain second-order field equations and stress tensors
- Imperfect Dark Energy from Kinetic Gravity Braiding
- Primordial Non-Gaussianities from Inflation Models
- G-inflation: inflation driven by the Galileon field
- Galileon inflation
- DBI and the Galileon reunited
- Non-Gaussianity in the modulated reheating scenario
- The shape of primordial non-Gaussianity and the CMB bispectrum
- Primordial trispectrum from inflation
- Symmetries for Galileons and DBI scalars on curved space
- Limits on f_NL parameters from WMAP 3yr data
- Primordial non-Gaussianity from the DBI Galileons
- CMB Constraints on Primordial non-Gaussianity from the Bispectrum (f_{NL}) and Trispectrum (g_{NL} and τ_{NL}) and a New Consistency Test of Single-Field Inflation
- Modified gravity a la Galileon: Late time cosmic acceleration and observational constraints
- General Embedded Brane Effective Field Theories
- Primordial non-Gaussianity from G-inflation
- Primordial fluctuations and non-Gaussianities from multifield DBI Galileon inflation
- A universal bound on N-point correlations from inflation
- Testing gravity with non-Gaussianity
- Constraining Modified Gravity with Large non-Gaussianities
Cited by in corpus (22)
- Beyond the Cosmological Standard Model
- Horndeski theory and beyond: a review
- Planck 2015 results. XVII. Constraints on primordial non-Gaussianity
- Features and New Physical Scales in Primordial Observables: Theory and Observation
- Shapes of primordial non-Gaussianities in the Horndeski's most general scalar-tensor theories
- Inflationary perturbation theory is geometrical optics in phase space
- Inflationary signatures of single-field models beyond slow-roll
- Reheating, Multifield Inflation and the Fate of the Primordial Observables
- Anatomy of bispectra in general single-field inflation -- modal expansions
- An Effective Cosmological Collider
- Primordial non-Gaussianities of gravitational waves beyond Horndeski
- General CMB bispectrum analysis using wavelets and separable modes
- A Modal Approach to the Numerical Calculation of Primordial non-Gaussianities
- Non-Gaussian Shape Recognition
- Why does the effective field theory of inflation work?
- Scalar Bispectrum Beyond Slow-Roll in the Unified EFT of Inflation
- Resonant non-Gaussianity with equilateral properties
- The Trispectrum in the Effective Theory of Inflation with Galilean symmetry
- Constraining Galileon Inflation
- Principal Components of CMB non-Gaussianity
- Optimal bispectrum constraints on single-field models of inflation
- Constraining fast-roll inflation