A Fake Instability in String Inflation

Abstract

In type IIB Fibre Inflation models the inflaton is a Kaehler modulus which is kinetically coupled to the corresponding axion. In this setup the curvature of the field space induces tachyonic isocurvature perturbations normal to the background inflationary trajectory. However we argue that the associated instability is unphysical since it is due to the use of ill-defined entropy variables. In fact, upon using the correct relative entropy perturbation, we show that in Fibre Inflation axionic isocurvature perturbations decay during inflation and the dynamics is essentially single-field.

arXiv comment5 pages + references, 3 figures

References in corpus (32)

• Planck 2018 results. X. Constraints on inflation
• Systematics of Moduli Stabilisation in Calabi-Yau Flux Compactifications
• A new approach to the evolution of cosmological perturbations on large scales
• Adiabatic and entropy perturbations from inflation
• Features of heavy physics in the CMB power spectrum
• Fibre Inflation: Observable Gravity Waves from IIB String Compactifications
• Non-minimal Inflationary Attractors
• General Analysis of LARGE Volume Scenarios with String Loop Moduli Stabilisation
• Primordial Black Holes from String Inflation
• Geometrical Destabilization of Inflation
• Adiabatic and entropy perturbations with interacting fluids and fields
• A covariant approach to general field space metric in multi-field inflation
• Oscillons from String Moduli
• Robust Inflation from Fibrous Strings
• Just enough inflation: power spectrum modifications at large scales
• A Geometrical Upper Bound on the Inflaton Range
• Toric K3-Fibred Calabi-Yau Manifolds with del Pezzo Divisors for String Compactifications
• Global Embedding of Fibre Inflation Models
• ${\alpha }^{\prime }$ Inflation: Moduli Stabilisation and Observable Tensors from Higher Derivatives
• Chiral Global Embedding of Fibre Inflation Models
• LARGE Volume String Compactifications at Finite Temperature
• Power Suppression at Large Scales in String Inflation
• Low-l CMB Power Loss in String Inflation
• Fibre Inflation and $\alpha$-attractors
• Inflating with Large Effective Fields
• On Non-Canonical Kinetic Terms and the Tilt of the Power Spectrum
• Reheating and Dark Radiation after Fibre Inflation
• Fitting string inflation to real cosmological data: the Fibre Inflation case
• Starobinsky-Type Inflation from ${\alpha }^{\prime }$-Corrections
• Geometrical Destabilisation of Ultra-Light Axions in String Inflation
• A geometrical instability for ultra-light fields during inflation?
• Fibre Inflation and Reheating

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• Chiral global embedding of Fibre Inflation with $\overline{D3}$ uplift
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