Khronon inflation

Abstract

We study the possibility that the approximate time shift symmetry during inflation is promoted to the full invariance under time reparametrization t \to \tilde t(t), or equivalently under field redefinition of the inflaton ϕ\to \tildeϕ(ϕ). The symmetry allows only two operators at leading order in derivatives, so that all n-point functions of scalar perturbations are fixed in terms of the power spectrum normalization and the speed of sound. During inflation the decaying mode only decays as 1/a and this opens up the possibility to violate some of the consistency relations in the squeezed limit, although this violation is suppressed by the (small) breaking of the field reparametrization symmetry. In particular one can get terms in the 3-point function that are only suppressed by 1/k_L in the squeezed limit k_L \to 0 compared to the local shape.

15 pages, 1 figure, v2. changes regarding the violation of the consistency relation. JCAP published version

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• The Effective Field Theory of Dark Energy
• The Observed Squeezed Limit of Cosmological Three-Point Functions
• Effective Description of Higher-Order Scalar-Tensor Theories
• Symmetries and Loops in Inflation
• Building a Boostless Bootstrap for the Bispectrum
• Weakly Broken Galileon Symmetry
• Light Particles with Spin in Inflation
• Slavnov-Taylor Identities for Primordial Perturbations
• Single-Field Consistency Relations of Large Scale Structure. Part III: Test of the Equivalence Principle
• Phenomenology of theories of gravity without Lorentz invariance: the preferred frame case
• The Physical Squeezed Limit: Consistency Relations at Order q^2
• Imprints of Oscillatory Bispectra on Galaxy Clustering
• Non-Trivial Checks of Novel Consistency Relations
• UV-extending Ghost Inflation
• Fracton gravity from spacetime dipole symmetry
• Canonical formulation of Poincare BFCG theory and its quantization
• Dimensionless physics: continuation
• Microcausality without Lorentz invariance
• Acoustic metric and Planck constants
• Inflationary perturbations with Lifshitz scaling
• Weakly Broken Galileon Symmetry in Cosmology