Sudden variations in the speed of sound during inflation: features in the power spectrum and bispectrum

Abstract

We employ the formalism of the effective field theory of inflation to study the effects of a sudden change in the speed of sound of the inflationary perturbations. Such an event generates a feature with high frequency oscillations both in the two- and in the three-point functions of the curvature fluctuations. We study, at first order in the magnitude of the change of the speed of sound, the dependence of the power spectrum and of the bispectrum on the duration of the change. In the limit of a very short duration, the oscillations in the power spectrum persist up to very large momenta and the amplitude of the feature in the bispectrum diverges while its location moves to increasing momenta.

7 pp, 2 figures

References in corpus (10)

• The Effective Field Theory of Inflation
• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• Generation and Characterization of Large Non-Gaussianities in Single Field Inflation
• Primordial fluctuations and non-Gaussianities in multi-field DBI inflation
• Non-Gaussianity from Step Features in the Inflationary Potential
• Cosmological Fluctuations from Infra-Red Cascading During Inflation
• Effects of particle production during inflation
• The scalar bi-spectrum in the Starobinsky model: The equilateral case
• Resonant Trispectrum and a Dozen More Primordial N-point functions
• The effect of varying sound velocity on primordial curvature perturbations

Cited by in corpus (35)

• Features and New Physical Scales in Primordial Observables: Theory and Observation
• On the importance of heavy fields during inflation
• The Science of the Einstein Telescope
• Correlating features in the primordial spectra
• Inflation with moderately sharp features in the speed of sound: GSR and in-in formalism for power spectrum and bispectrum
• Warp Features in DBI Inflation
• The Effective Field Theory of Inflation Models with Sharp Features
• Localized correlated features in the CMB power spectrum and primordial bispectrum from a transient reduction in the speed of sound
• Bispectrum in Single-Field Inflation Beyond Slow-Roll
• Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies
• Propagating speed of primordial gravitational waves and inflation
• Is there an effect of a nontrivial $c_T$ during inflation?
• Steps to Reconcile Inflationary Tensor and Scalar Spectra
• Strong scale dependent bispectrum in the Starobinsky model of inflation
• Testing Inflation and Curvaton Scenarios with CMB Distortions
• Cosmic inflation in a landscape of heavy-fields
• Searching for primordial localized features with CMB and LSS spectra
• Higher order derivative coupling to gravity and its cosmological implications
• Curvature Perturbations from a Massive Vector Curvaton
• Inflation in a two 3-form fields scenario
• Local non-Gaussianity from rapidly varying sound speeds
• Perturbative Unitarity of Inflationary Models with Features
• Featuring the primordial power spectrum: new constraints on interrupted slow-roll from CMB and LRG data
• Induced Gravitational Waves from Multi-Sound Speed Resonances during Cosmological Inflation
• High-resolution CMB bispectrum estimator with flexible modal basis
• Primordial power spectrum features in phenomenological descriptions of inflation
• Consistency relations for sharp inflationary non-Gaussian features
• Sensitivity of inflationary predictions to pre-inflationary phases
• Coupling structure of multi-field primordial perturbations
• Jump in fluid properties of inflationary universe to reconcile scalar and tensor spectra
• Enhanced spectrum of primordial perturbations, galaxy formation and small scale structure
• Superimposed Oscillations in Brane Inflation
• Log-periodic gravitational-wave background beyond Einstein gravity
• Application of beyond $\delta N$ formalism -- Varying sound speed
• The running of featureful primordial power spectra