Inflation with multiple sound speeds: a model of multiple DBI type actions and non-Gaussianities

Abstract

In this letter we study adiabatic and isocurvature perturbations in the frame of inflation with multiple sound speeds involved. We suggest this scenario can be realized by a number of generalized scalar fields with arbitrary kinetic forms. These scalars have their own sound speeds respectively, so the propagations of field fluctuations are individual. Specifically, we study a model constructed by two DBI type actions. We find that the critical length scale for the freezing of perturbations corresponds to the maximum sound horizon. Moreover, if the mass term of one field is much lighter than that of the other, the entropy perturbation could be quite large and so may give rise to a growth outside sound horizon. At cubic order, we find that the non-Gaussianity of local type is possibly large when entropy perturbations are able to convert into curvature perturbations. We also calculate the non-Gaussianity of equilateral type approximately.

11 pages, 1 figure

References in corpus (29)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• Generation and Characterization of Large Non-Gaussianities in Single Field Inflation
• Primordial perturbations and non-Gaussianities in DBI and general multi-field inflation
• Perturbations in generalized multi-field inflation
• Primordial fluctuations and non-Gaussianities in multi-field DBI inflation
• Non-Gaussianities in New Ekpyrotic Cosmology
• Multiple field inflation
• Non-Gaussianities from ekpyrotic collapse with multiple fields
• Spinflation
• Multifield DBI Inflation and Non-Gaussianities
• Energy Transfer in Multi Field Inflation and Cosmological Perturbations
• Nflation: multi-field inflationary dynamics and perturbations
• Curvaton Dynamics and the Non-Linearity Parameters in Curvaton Model
• Large Non-Gaussianity Implication for Curvaton Scenario
• Speedy sound and cosmic structure
• General Single Field Inflation with Large Positive Non-Gaussianity
• On Perturbation Spectra of N-flation
• DBI-Curvaton
• Is Brane Inflation Eternal?
• Near Scale Invariance with Modified Dispersion Relations
• IR Inflation from Multiple Branes
• Consistency Relations for Non-Gaussianity
• DBI N-flation
• DBI Inflation using a One-Parameter Family of Throat Geometries
• Multiple scalar particle decay and perturbation generation
• Cosmological perturbations from multi-field inflation
• On Number of Nflation Fields
• Assisted chaotic inflation in brane-world cosmology

Cited by in corpus (91)

• Primordial Non-Gaussianities from Inflation Models
• Quasi-Single Field Inflation and Non-Gaussianities
• Particle physics models of inflation and curvaton scenarios
• Review of local non-Gaussianity from multi-field inflation
• Primordial non-Gaussianity from the DBI Galileons
• When Primordial Black Holes from Sound Speed Resonance Meet a Stochastic Background of Gravitational Waves
• Non-Gaussianity beyond slow roll in multi-field inflation
• Primordial black holes from sound speed resonance in the inflaton-curvaton mixed scenario
• Evolution of Metric Perturbations in Quintom Bounce model
• On the full trispectrum in single field DBI-inflation
• On Classification of Models of Large Local-Type Non-Gaussianity
• Inflation in Entropic Cosmology: Primordial Perturbations and non-Gaussianities
• Cosmological Bootstrap in Slow Motion
• Inflation with moderately sharp features in the speed of sound: GSR and in-in formalism for power spectrum and bispectrum
• A note on the role of the boundary terms for the non-Gaussianity in general k-inflation
• A geometric description of the non-Gaussianity generated at the end of multi-field inflation
• Primordial perturbation with a modified dispersion relation
• Bootstrapping Multi-Field Inflation: non-Gaussianities from light scalars revisited
• Primordial fluctuations and non-Gaussianities from multifield DBI Galileon inflation
• Non-Gaussianity from violation of slow-roll in multiple inflation
• On the full quantum trispectrum in multi-field DBI inflation
• Warm DBI Inflation
• Dirac-Born-Infeld realization of sound speed resonance mechanism for primordial black holes
• Large and strong scale dependent bispectrum in single field inflation from a sharp feature in the mass
• Combined local and equilateral non-Gaussianities from multifield DBI inflation
• Generalised DBI-Quintessence
• N-flation from multiple DBI type actions
• CMB Power Asymmetry from Primordial Sound Speed Parameter
• Non-Gaussianities in Multifield Inflation: Superhorizon Evolution, Adiabaticity, and the Fate of fnl
• Primordial Non-Gaussianities from the Trispectra in Multiple Field Inflationary Models
• Strong scale dependent bispectrum in the Starobinsky model of inflation
• Quantum Standard Clocks in the Primordial Trispectrum
• On Non-Gaussianities in Multi-Field Inflation (N fields): Bi- and Tri-spectra beyond Slow-Roll
• Trispectrum from Ghost Inflation
• D-brane Potentials in the Warped Resolved Conifold and Natural Inflation
• Cosmology of the Spinor Emergent Universe and Scale-invariant Perturbations
• Non-Gaussianities of Single Field Inflation with Non-minimal Coupling
• Note on Non-Gaussianities in Two-field Inflation
• Large Nonlocal Non-Gaussianity from a Curvaton Brane
• Quintessence dynamics with two scalar fields and mixed kinetic terms
• Inflationary predictions in scalar-tensor DBI inflation
• Quintessence and phantom dark energy from ghost D-branes
• Bispectra from two-field inflation using the long-wavelength formalism
• Inflation in a Web
• On Cross-correlations between Curvature and Isocurvature Perturbations during Inflation
• Adiabaticity and the Fate of Non-Gaussianities: The Trispectrum and Beyond
• Local non-Gaussianity from rapidly varying sound speeds
• Cold Dark Matter Isocurvature Perturbations: Cosmological Constraints and Applications
• Non-Gaussianity from Lifshitz Scalar
• Loop Corrections to Cosmological Perturbations in Multi-field Inflationary Models
• Rotating a Curvaton Brane in a Warped Throat
• Fields Annihilation and Particles Creation in DBI inflation
• Gauged M-flation After BICEP2
• Production of non-gaussianities in a bouncing phase
• On Non-Gaussianities in Two-Field Poly-Instanton Inflation
• Numerical study of inflationary preheating with arbitrary power-law potential and a realization of curvaton mechanism
• Quadra-Spectrum and Quint-Spectrum from Inflation and Curvaton Models
• Effective metric in nonlinear scalar field theories
• Primordial power spectra from $k$-inflation with curvature
• Mixed non-Gaussianity in multiple-DBI inflation
• Embedding DBI inflation in scalar-tensor theory
• Non-Gaussianity from false vacuum inflation: Old curvaton scenario
• Evolution of curvature perturbation in generalized gravity theories
• Scale-dependent CMB power asymmetry from primordial speed of sound and a generalized $\delta$N formalism
• On primordial trispectrum from exchanging scalar modes in general multiple field inflationary models
• Non-Gaussianity in multi-sound-speed disformally coupled inflation
• Testing the scale-dependent hemispherical asymmetry with the 21-cm power spectrum from the epoch of reionization
• Effect of intermediate Minkowskian evolution on CMB bispectrum
• Dynamics of Cosmological Perturbations in Multi-Speed Inflation
• Momentum dependence of the bispectrum in two-field inflation
• Preheating in a DBI Inflation Model
• Covariant second-order perturbations in generalized two-field inflation
• Higher Order Corrections to Asymptotic-de Sitter Inflation
• Revised $f_{\mathrm{NL}}$ parameter in Curvaton Scenario
• Schwinger-Keldysh mechanism in extended quasi single field inflation
• Testing the Lorentz and CPT Symmetry with CMB polarizations and a non-relativistic Maxwell Theory
• Scale dependences of local form non-Gaussianity parameters from a DBI isocurvature field
• Non-relativistic Matrix Inflation
• Multi-scalar tachyon potential on non-BPS domain walls
• Constraining Inflationary Scenarios with Braneworld Models and Second Order Cosmological Perturbations
• Cosmological singularities in non-canonical models of dark energy
• The Non-Adiabatic Pressure Perturbation and Non-Canonical Kinetic Terms in Multifield Inflation
• Getting inflationary models using the deformation method
• Ultra-light dark matter with non-canonical kinetics reopening the mass window
• The adiabatic/entropy decomposition in $P({\varphi }^I,X^{IJ})$ theories with multiple sound speeds
• Second-order cosmological perturbations in two-field inflation and predictions for non-Gaussianity
• Cosmological Perturbations in Inflationary Models with Anisotropic Space-Time Scaling in Lifshitz Background
• Non-Gaussianity in Cosmology: from Inflation to the CMB
• Inhomogeneous Reheating Scenario with DBI fields
• Multi-brid DBI Inflation
• Searching for dark matter isocurvature initial conditions with N-body Simulations