Negative running prevents eternal inflation

Abstract

Current data from the Planck satellite and the BICEP2 telescope favor, at around the $2\sigma$ level, negative running of the spectral index of curvature perturbations from inflation. We show that for negative running $\alpha <0$, the curvature perturbation amplitude has a maximum on scales larger than our current horizon size. A condition for the absence of eternal inflation is that the curvature perturbation amplitude always remain below unity on superhorizon scales. For current bounds on $n_{\mathrm{S}}$ from Planck, this corresponds to an upper bound of the running $\alpha <-4\times 10^{-5}$, so that even tiny running of the scalar spectral index is sufficient to prevent eternal inflation from occurring, as long as the running remains negative on scales outside the horizon. In single-field inflation models, negative running is associated with a finite duration of inflation: we show that eternal inflation may not occur even in cases where inflation lasts as long as $10^4$ e-folds.

arXiv commentV2: Version submitted to JCAP

References in corpus (53)

• Planck 2013 results. XVI. Cosmological parameters
• Cosmological parameters from CMB and other data: a Monte-Carlo approach
• BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• Planck 2013 results. XXII. Constraints on inflation
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• The WiggleZ Dark Energy Survey: mapping the distance-redshift relation with baryon acoustic oscillations
• Planck 2013 results. XV. CMB power spectra and likelihood
• Planck 2013 results. XXIII. Isotropy and statistics of the CMB
• Suppressing the lower Multipoles in the CMB Anisotropies
• MSSM flat direction inflation: slow roll, stability, fine tunning and reheating
• Punctuated inflation and the low CMB multipoles
• Neutrinos help reconcile Planck measurements with both Early and Local Universe
• Relic Neutrinos, thermal axions and cosmology in early 2014
• Non-Bunch-Davies Initial State Reconciles Chaotic Models with BICEP and Planck
• The tensor-to-scalar ratio in punctuated inflation
• The pre-inflationary vacuum in the cosmic microwave background
• Whipped inflation
• Inflation with a running spectral index in supergravity
• Sterile neutrinos help reconcile the observational results of primordial gravitational waves from Planck and BICEP2
• Spatial Curvature Falsifies Eternal Inflation
• Kinetic Initial Conditions for Inflation
• Inflation after False Vacuum Decay: Observational Prospects after Planck
• Low & High scale MSSM inflation, gravitational waves and constraints from Planck
• What Can WMAP Tell Us About The Very Early Universe? New Physics as an Explanation of Suppressed Large Scale Power and Running Spectral Index
• CMB quadrupole suppression: I. Initial conditions of inflationary perturbations
• Universality in D-brane Inflation
• Cosmological constraints on neutrinos after BICEP2
• Inflection point inflation within supersymmetry
• The Knotted Sky II: Does BICEP2 require a nontrivial primordial power spectrum?
• Predictions of just-enough inflation
• Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies
• Power Suppression at Large Scales in String Inflation
• Ruling out the power-law form of the scalar primordial spectrum
• Low power on large scales in just enough inflation models
• Steps to Reconcile Inflationary Tensor and Scalar Spectra
• CMB anomalies from an inflationary model in string theory
• The challenge for single field inflation with BICEP2 result
• Reconstructing inflationary potential from BICEP2 and running of tensor modes
• Reconstruction of the primordial power spectra with Planck and BICEP2
• On quantifying and resolving the BICEP2/Planck tension over gravitational waves
• The large scale CMB cut-off and the tensor-to-scalar ratio
• Inflation After False Vacuum Decay: New Evidence from BICEP2
• Modeling Quantum Gravity Effects in Inflation
• Tensor to scalar ratio and large scale power suppression from pre-slow roll initial conditions
• Inflection Points and the Power Spectrum
• Chaotic inflation with curvaton induced running
• Isocurvature perturbations and tensor mode in light of Planck and BICEP2
• Negative Running of the Spectral Index, Hemispherical Asymmetry and the Consistency of Planck with Large $r$
• CMB, Quantum Fluctuations and the Predictive Power of Inflation
• Radiative Corrections to the Inflaton Potential as an Explanation of Suppressed Large Scale Power in Density Perturbations and the Cosmic Microwave Background
• Effect of the length of inflation on angular TT and TE power spectra in power-law inflation
• Reconciling the Tension Between Planck and BICEP2 Through Early Dark Energy

Cited by in corpus (12)

• Blue Tensor Spectrum from Particle Production during Inflation
• Eternal Hilltop Inflation
• Trans-Planckian censorship and single-field inflaton potential
• Power Spectrum of Inflationary Attractors
• Eternal inflation in a dissipative and radiation environment: Heated demise of eternity
• Lyth Bound, eternal inflation and future cosmological missions
• Radiative Corrections from Heavy Fast-Roll Fields during Inflation
• B-modes and the sound speed of primordial fluctuations
• Defying eternal inflation in warm inflation with a negative running
• Non-perpetual Eternal Inflation and the Emergent de Sitter Swampland Conjecture
• Primordial magnetic fields in the $f^{2}FF$ model in large field inflation under de Sitter and power law expansion
• Confronting Mukhanov Parametrization of Inflationary Equation-of-State with ACT-DR6