The spatial gauge-dependence of single-field inflationary bispectra

Abstract

In single-field inflationary models the bispectra are usually given in the $\zeta$-gauge, because its temporal part leads to the super-horizon conservation of fluctuations. However, this property is independent of the choice of {\it spatial} gauge, so in this letter we explore this freedom. We compute the variation of the bispectra under the most general spatial gauge transformation that is globally defined and privileges no point, direction or scale. In the squeezed configuration we then obtain a generalization of the classic $\zeta$-gauge consistency relations, which we also derive through the `large diffeomorphism' approach for all four bispectra. At leading order in the long wave-number the transformation only affects the case where the long mode is a scalar. The first effect is a shift of the tilt factor, so that one can significantly reduce the amplitude of that contribution. Secondly, there is now an extra term depending on the triangle shape, the same as in solid inflation, which is due to the fact that the 3-metric has a scalar anisotropy in generic spatial gauge. At next-to-leading order there is no variation, so the conformal consistency relations of the $\zeta$-gauge are preserved.

7 pages, matches published version

References in corpus (9)

• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• The imprints of primordial non-gaussianities on large-scale structure: scale dependent bias and abundance of virialized objects
• Primordial Non-Gaussianities from Inflation Models
• On the consistency relation of the 3-point function in single field inflation
• Conformal Symmetries of Adiabatic Modes in Cosmology
• The Inflationary Trispectrum for Models with Large Non-Gaussianities
• A new method for calculating the primordial bispectrum in the squeezed limit
• Classicality of the primordial perturbations
• Conservation of the nonlinear curvature perturbation in generic single-field inflation

Cited by in corpus (3)

• The Physical Content of Long Tensor Modes in Cosmology
• Incompatibility of Standard Galaxy Bias Models in General Relativity
• Non-Gaussianity in the Squeezed Three-Point Correlation from the Relativistic Effects