Heavy fields, reduced speeds of sound and decoupling during inflation

Abstract

We discuss and clarify the validity of effective single field theories of inflation obtained by integrating out heavy degrees of freedom in the regime where adiabatic perturbations propagate with a suppressed speed of sound. We show by construction that it is indeed possible to have inflationary backgrounds where the speed of sound remains suppressed and slow-roll persists for long enough. In this class of models, heavy fields influence the evolution of adiabatic modes in a manner that is consistent with decoupling of physical low and high energy degrees of freedom. We emphasize the distinction between the effective masses of the isocurvature modes and the eigenfrequencies of the propagating high energy modes. Crucially, we find that the mass gap that defines the high frequency modes increases with the strength of the turn, even as the naive heavy (isocurvature) and light (curvature) modes become more strongly coupled. Adiabaticity is preserved throughout, and the derived effective field theory remains in the weakly coupled regime, satisfying all current observational constraints on the resulting primordial power spectrum. In addition, these models allow for an observably large equilateral non-Gaussianity.

arXiv comment8 pages, v2: minor changes, typos corrected

References in corpus (24)

• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• The Effective Field Theory of Inflation
• Quantum Gravity in Everyday Life: General Relativity as an Effective Field Theory
• Adiabatic and entropy perturbations from inflation
• Effective Field Theory for Inflation
• Features of heavy physics in the CMB power spectrum
• Large non-Gaussianities with Intermediate Shapes from Quasi-Single Field Inflation
• Scalar perturbations during multiple-field slow-roll inflation
• Equilateral Non-Gaussianity and New Physics on the Horizon
• The Gelaton Scenario: Equilateral non-Gaussianity from multi-field dynamics
• Quasi-Single Field Inflation with Large Mass
• Effective theories of single field inflation when heavy fields matter
• Mass hierarchies and non-decoupling in multi-scalar field dynamics
• On the importance of heavy fields during inflation
• Are Inflationary Predictions Sensitive to Very High Energy Physics?
• Strongly Coupled Perturbations in Two-Field Inflationary Models
• Curvature Perturbation Spectrum in Two-field Inflation with a Turning Trajectory
• Effective Field Theory and Decoupling in Multi-field Inflation: An Illustrative Case Study
• Influence of heavy modes on perturbations in multiple field inflation
• Effective Field Theories and Inflation
• Density perturbations arising from multiple field slow-roll inflation
• Decoupling Survives Inflation: A Critical Look at Effective Field Theory Violations During Inflation
• On Non-Canonical Kinetic Terms and the Tilt of the Power Spectrum

Cited by in corpus (112)

• Scalaron from $R^2$-gravity as a Heavy Field
• Features and New Physical Scales in Primordial Observables: Theory and Observation
• Quasi-Single Field Inflation with Large Mass
• Seeding primordial black holes in multifield inflation
• The string swampland constraints require multi-field inflation
• Signs of Analyticity in Single-Field Inflation
• Inflation in the Mixed Higgs-$R^2$ Model
• Influence of heavy modes on perturbations in multiple field inflation
• Equilateral non-Gaussianity from heavy fields
• An effective field theory during inflation: reduced density matrix and its quantum master equation
• Imprints of Massive Primordial Fields on Large-Scale Structure
• Primordial Black Holes in Higgs-$R^2$ Inflation as a Whole Dark Matter
• Correlating features in the primordial spectra
• Quasi Single Field Inflation in the non-perturbative regime
• Inflating in a Trough: Single-Field Effective Theory from Multiple-Field Curved Valleys
• Primordial fluctuations and non-Gaussianities in sidetracked inflation
• Inflation with moderately sharp features in the speed of sound: GSR and in-in formalism for power spectrum and bispectrum
• An effective field theory during inflation II: stochastic dynamics and power spectrum suppression
• Bootstrapping Multi-Field Inflation: non-Gaussianities from light scalars revisited
• Effective field theory of weakly coupled inflationary models
• The Effective Field Theory of Inflation Models with Sharp Features
• Low-Energy Effective Field Theory for Chromo-Natural Inflation
• Hyper non-Gaussianities in inflation with strongly non-geodesic motion
• Multi-field inflation and cosmological perturbations
• The rapid-turn inflationary attractor
• Dirac-Born-Infeld realization of sound speed resonance mechanism for primordial black holes
• Angular inflation in multi-field $\alpha$-attractors
• Cumulative effects in inflation with ultra-light entropy modes
• Precise measurements of inflationary features with 21 cm observations
• Numerical evaluation of the bispectrum in multiple field inflation
• Landscape tomography through primordial non-Gaussianity
• Bispectrum in Single-Field Inflation Beyond Slow-Roll
• Sound Speed of Primordial Fluctuations in Supergravity Inflation
• Breaking discrete symmetries in the effective field theory of inflation
• Oscillatory features in the curvature power spectrum after a sudden turn of the inflationary trajectory
• Large power spectrum and primordial black holes in the effective theory of inflation
• Backreaction and Stochastic Effects in Single Field Inflation
• Planck and BICEP/Keck Array 2018 constraints on primordial gravitational waves and perspectives for future B-mode polarization measurements
• Mass Hierarchies and Dynamical Field Range
• Steps to Reconcile Inflationary Tensor and Scalar Spectra
• On the Effective Field Theory for Quasi-Single Field Inflation
• Untangling features in the primordial spectra
• Warm Quasi-Single Field Inflation
• Universality and scaling in multi-field $\alpha$-attractor preheating
• Testing Inflation and Curvaton Scenarios with CMB Distortions
• Correlating correlation functions of primordial perturbations
• Multi-field dark energy: cosmic acceleration on a steep potential
• Cosmic inflation in a landscape of heavy-fields
• Effective perfect fluids in cosmology
• Fat Inflatons, Large Turns and the $\eta$-problem
• Primordial spectra from sudden turning trajectory
• Probing Two-Field Open Inflation by Resonant Signals in Correlation Functions
• Mild Non-Gaussianities under Perturbative Control from Rapid-Turn Inflation Models
• Bounds on non-adiabatic evolution in single-field inflation
• Multi-field Inflation in High-Slope Potentials
• On the viability of m**2 phi**2 and natural inflation
• A Tip for Landscape Riders: Multi-Field Inflation Can Fulfill the Swampland Distance Conjecture
• On the integration of fields and quanta in time dependent backgrounds
• The Inflaton that Could : Primordial Black Holes and Second Order Gravitational Waves from Tachyonic Instability induced in Higgs-$R^2$ Inflation
• Consistency relations for sharp features in the primordial spectra
• Bayesian reconstruction of the inflaton's speed of sound using CMB data
• Hybrid Quasi-Single Field Inflation
• Injection of a single electron from static to moving quantum dots
• Higher derivatives and power spectrum in effective single field inflation
• Correlating CMB Spectral Distortions with Temperature: what do we learn on Inflation?
• Angular Correlation Functions for Models with Logarithmic Oscillations
• The effect of multiple features on the power spectrum in two-field inflation
• Non-canonical inflation coupled to matter
• Non-Gaussianities in models of inflation with large and negative entropic masses
• Gravitational Production of Completely Dark Photons with Nonminimal Couplings to Gravity
• On degenerate models of cosmic inflation
• Robust predictions for an oscillatory bispectrum in Planck 2015 data from transient reductions in the speed of sound of the inflaton
• Sudden braking and turning with a two-field potential bump: primordial black hole formation
• Combined features in the primordial spectra induced by a sudden turn in two-field DBI inflation
• Cosmological dynamics of multifield dark energy
• Completely Dark Matter from Rapid-Turn Multifield Inflation
• Primordial feature constraints from BOSS+eBOSS
• Local random potentials of high differentiability to model the Landscape
• Magnon Inflation: Slow Roll with Steep Potentials
• A Smooth Landscape: Ending Saddle Point Inflation Requires Features to be Shallow
• The Massive Flat Space Limit of Cosmological Correlators
• Non-Gaussianities in a two-field generalization of Natural Inflation
• Scale-dependent hemispherical asymmetry from general initial state during inflation
• Primordial gravitational wave phenomenology with polarized Sunyaev Zel'dovich tomography
• (Slow-)Twisting inflationary attractors
• Correlated primordial spectra in effective theory of inflation
• Coupling structure of multi-field primordial perturbations
• Reconstructing the EFT of Inflation from Cosmological Data
• A Universal Bound on Excitations of Heavy Fields during Inflation
• (Super)Universal Attractors and the de Sitter Vacua in String Landscape
• Enhanced power spectra from multi-field inflation
• Multiple Field Inflation and Signatures of Heavy Physics in the CMB
• Radiative Corrections from Heavy Fast-Roll Fields during Inflation
• Model-independent approach to effective sound speed in multi-field inflation
• Flattened Axion Monodromy Beyond Two Derivatives
• Moduli backreaction and supersymmetry breaking in string-inspired inflation models
• Quintom fields from chiral anisotropic cosmology
• B-modes and the sound speed of primordial fluctuations
• Generalizing the Swampland: Embedding $P(X,\phi )$ Inflationary Theories in a Curved Multi-field Space
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• Loops in inflation with strongly non-geodesic motion
• Generalised conditions for rapid-turn inflation
• The UV Sensitivity of Axion Monodromy Inflation
• Cosmological perturbations in the spatially covariant gravity with a dynamical lapse function
• The hand-made tail: Non-perturbative tails from multifield inflation
• On the Square Speed of Sound in High-Energy Collisions: Range of Values and How to Understand It
• Inflation with vector fields revisited: heavy entropy perturbations and primordial black holes
• Towards a de Sitter quintom-like cosmology from a reduction of a 7-dimensional $BF$ theory
• Primordial gravitational waves from excited states
• Accelerated expansion in the effective field theory of a radiation dominated universe
• Primordial black holes with anisotropic hair
• On the importance of heavy fields in pseudo-scalar inflation