REVIEW 30 cited by
Adiabatic and entropy perturbations from inflation
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
read the original abstract
We study adiabatic (curvature) and entropy (isocurvature) perturbations produced during a period of cosmological inflation that is driven by multiple scalar fields with an arbitrary interaction potential. A local rotation in field space is performed to separate out the adiabatic and entropy modes. The resulting field equations show explicitly how on large scales entropy perturbations can source adiabatic perturbations if the background solution follows a curved trajectory in field space, and how adiabatic perturbations cannot source entropy perturbations in the long-wavelength limit. It is the effective mass of the entropy field that determines the amplitude of entropy perturbations during inflation. We present two applications of the equations. First, we show why one in general expects the adiabatic and entropy perturbations to be correlated at the end of inflation, and calculate the cross-correlation in the context of a double inflation model with two non-interacting fields. Second, we consider two-field preheating after inflation, examining conditions under which entropy perturbations can alter the large-scale curvature perturbation and showing how our new formalism has advantages in numerical stability when the background solution follows a non-trivial trajectory in field space.
Forward citations
Cited by 30 Pith papers
-
Pushing the Primordial Frontier: Exact Linear Solutions in Multifield Inflation
Exact analytic solutions for coupled linear perturbations in two-field inflation provide a closed-form primordial power spectrum that interpolates weak, strong, light, and heavy field regimes.
-
Phase-resolved field-space distance criteria in ekpyrotic, bouncing and cyclic cosmologies
Proposes phase-resolved invariant path-length criteria and a master formula for lower bound on ε_ek in ekpyrotic cosmologies, using BKL suppression and conversion windows as constraints.
-
Isocurvature Induced Gravitational Waves at Pulsar Timing Arrays
The work shows that free-streaming dark radiation isocurvature produces a qualitatively different gravitational wave spectrum than cold dark matter isocurvature and derives constraints on isocurvature power spectra ar...
-
Extending the Dynamical Systems Toolkit: Coupled Fields in Multiscalar Dark Energy
New dynamical systems variables for coupled axion-saxion fields yield a general non-geodesicity expression at fixed points and identify genuinely non-geodesic attractors under exponential couplings.
-
Mild Non-Gaussianities under Perturbative Control from Rapid-Turn Inflation Models
Leading-order exponential contributions to higher-order correlators in rapid-turn inflation cancel exactly in the in-in formalism, leaving order-one non-Gaussianity and preserving perturbative control.
-
Spectator Axions in String Inflation and Primordial Black Holes
In Fibre Inflation, spectator axions with f≲0.1 M_Pl leave the PBH power spectrum unchanged, while for f≳0.1 M_Pl and exponentially small non-perturbative prefactors they can raise P_R from 1.9e-4 to 3.5e-3 and enable...
-
Axion isocurvature and the model-building problem of low-scale inflation
A light pre-inflationary QCD axion that is all the dark matter forces the inflationary Hubble scale below ~10^7–10^10 GeV and, for canonical slow-roll inflation, confines the inflaton to sub-10^-4 M_Pl of field motion...
-
Is there ghost and tachyon free bounce in UV complete gravity theory?
Ghost- and tachyon-free bounces in AID gravity require a negative cosmological constant; known positive-Λ solutions inevitably contain ghost radiation.
-
Superhorizon curvature perturbations in hybrid inflation revisited
Hybrid inflation's waterfall tachyonic instability grows isocurvature modes that convert to curvature perturbations at the field-space turn, yielding a k^{3}-peaked spectrum with always-positive f_NL that enhances PBH...
-
Cosmological gravitational particle production in multifield inflation
Negative field-space curvature enhances post-inflationary Ricci scalar oscillations and boosts CGPP dark matter number density by up to an order of magnitude relative to flat field-space cases, with nontrivial relic a...
-
Controlled Penumbral Inflation from Monodromic Valleys
Local branch data determine controlled inflation in monodromic penumbral valleys when Δ > 0 and p < 2 (or p=2 with large A_pm), with a minimal exactly solvable family provided.
-
Ultra slow-turn inflation
In slow-roll multi-field inflation, stability should be read from the total entropy perturbation, which decays in 'ultra slow-turn' models even when the isocurvature effective mass-squared is negative.
-
Inflation with a Growing Fifth Dimension
Inflation from a UV-brane inflaton in a warped 5D bulk with an IR brane predicts a blue-tilted low-k scalar spectrum and oscillating tensor features because the early adiabatic modes come from the radion.
-
Two-field mimetic gravity revisited and Hamiltonian analysis
A two-field mimetic gravity model has two scalar degrees of freedom, not one, and the extra entropy mode is a ghost when the fields have opposite-sign kinetic terms.
-
Origin of ultra-light fields during inflation and their suppressed non-Gaussianity
A scaling symmetry in a class of two-field inflation models naturally produces a massless isocurvature field whose self-interactions are suppressed, making primordial non-Gaussianity slow-roll suppressed but with a sq...
-
Orbital Inflation: inflating along an angular isometry of field space
Orbital Inflation reconstructs two-field actions with an angular isometry yielding single-field-like predictions that violate consistency relations and allow f_NL from slow-roll suppressed to O(few) depending on entro...
-
Penumbral Inflation from Calabi-Yau Boundaries
A string-theoretic construction maps Calabi-Yau boundary data into a logarithmic plateau inflation model, yielding the leading tensor-to-scalar prediction r = 4d/(q²N²) with Hodge degree d.
-
Cosmological perturbations and clustering mechanisms in multifield dark energy
Multifield dark energy with curved field space produces three clustering channels—sound-speed suppression, heavy-mode excitation, and curvature-driven tachyons—with distinct imprints on P(k) and the CMB.
-
Constraints on the Sum of Neutrino Masses from ACT DR6 and DESI DR2 Considering Isocurvature Initial Conditions
Including neutrino density isocurvature in fits to ACT DR6, DESI DR2, and DES data yields ∑m_ν < 0.057 eV at 95% CL in ΛCDM with no detection of the isocurvature mode.
-
On the Validity of the Effective Theory of (Multi-)Field Inflation
Computes perturbation amplitudes in general effective multi-field inflation without sub-horizon limit and bounds higher-derivative corrections via ε for finite-cutoff models.
-
Axion Perturbations: A General Analytical Treatment
Axion dark-matter perturbations are determined entirely by the homogeneous axion background's dependence on its initial misalignment angle, plus Weinberg's universal adiabatic-mode term.
-
Quasi-dust ekpyrotic scenario in Loop Quantum Cosmology
A quasi-dust ekpyrotic two-field model in Loop Quantum Cosmology produces viable primordial power spectra via coupled scalar and tensor perturbations.
-
Analysis of inflationary models in higher-dimensional uniform inflation
In (D+4)-dimensional uniform inflation the spectral index and tensor-to-scalar ratio are ns=1-(D+6)ε+2η and r=8(D+2)ε, which excludes D≥2 for the five models studied while allowing D=1 in the b0k >> 1 branch.
-
A complete analysis of inflation with piecewise quadratic potential
A new parameter alpha governs the amplitude, slope, and dip of the curvature power spectrum in piecewise quadratic two-stage inflation, with maximum growth k^5(log k)^2.
-
Stochastic inflation and non-perturbative power spectrum beyond slow roll
A numerical stochastic ΔN code reproduces the slow-roll power spectrum and shows that the time-independent non-perturbative spectrum fails at ultra-slow-roll transitions.
-
Fat Inflatons, Large Turns and the $\eta$-problem
Heavy scalar fields can still drive slow-roll inflation if the trajectory turns rapidly, evading the eta-problem; a D5-brane in a warped throat provides a concrete realization.
-
A multi-axion model of inflation and dark matter
A 300-mode Kaluza-Klein axion tower is proposed as a unified inflaton and dark-matter sector, but the lightest state's quoted lifetime contradicts the paper's own decay-rate formula.
-
A cross-epoch endpoint-consistency test of a single effective scaling from dark energy to inflation
A single power-law effective scaling anchored at today's Hubble rate is extrapolated to inflation and required to match the Starobinsky plateau within O(1) factors, selecting γ ≈ 0.49 and β ≈ 0.68.
-
Exploring Gravitational Wave Signatures Due to Primordial Non-gaussianity and Large Scale Structure Using SKAO
Explores SKAO detection of scalar-induced GW backgrounds as probes of primordial non-Gaussianity and parity violation, with LSS cross-correlation to improve SNR.
-
The Scale Factor Potential Approach to Inflation
The paper reparametrizes slow-roll inflation through a scale factor potential and constructs an example potential, but the chosen 60 e-fold branch is inconsistent with its own first-minimum end condition.
Discussion (0). Continue with ORCID to comment.