Quantum Gravity Constraints on Inflation

Abstract

We study quantum gravity constraints on inflationary model building. Our approach is based on requiring the entropy associated to a given inflationary model to be less than that of the de Sitter entropy. We give two prescriptions for determining the inflationary entropy, based on either `bits per unit area' or entanglement entropy. The existence of transPlanckian flat directions, necessary for large tensor modes in the CMB, correlates with an inflationary entropy greater than that allowed by de Sitter space. Independently these techniques also constrain or exclude de Sitter models with large-rank gauge groups and high UV cutoffs, such as racetrack inflation or the KKLT construction.

22 pages; v2 references added

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Cited by in corpus (36)

• Axion Cosmology
• Backreacted Axion Field Ranges in String Theory
• D7-Brane Chaotic Inflation
• Weak Gravity Strongly Constrains Large-Field Axion Inflation
• The Swampland Conjecture and F-term Axion Monodromy Inflation
• String Inflation After Planck 2013
• PBH dark matter from axion inflation
• The asymptotic dS Swampland Conjecture - a simplified derivation and a potential loophole
• A note on obstinate tachyons in classical dS solutions
• Large-Field Inflation with Multiple Axions and the Weak Gravity Conjecture
• Axion Monodromy and the Weak Gravity Conjecture
• On the validity of the perturbative description of axions during inflation
• D7-Brane Moduli Space in Axion Monodromy and Fluxbrane Inflation
• Flat Monodromies and a Moduli Space Size Conjecture
• Can Gravitational Instantons Really Constrain Axion Inflation?
• A Systematic Approach to Kähler Moduli Stabilisation
• Hypernatural inflation
• N-flation with Hierarchically Light Axions in String Compactifications
• The Spectrum of the Axion Dark Sector
• Small Field Polynomial Inflation: Reheating, Radiative Stability and Lower Bound
• Inflating with Large Effective Fields
• Towards Axion Monodromy Inflation with Warped KK-Modes
• On the weak gravity conjecture in string theory with broken supersymmetry
• The present and future of the most favoured inflationary models after $Planck$ 2015
• Large Field Inflation and Gravitational Entropy
• Evading the Lyth Bound in Hybrid Natural Inflation
• Axion decay constants away from the lamppost
• Phenomenological approaches of inflation and their equivalence
• Theoretical bounds on the tensor-to-scalar ratio in the cosmic microwave background
• Constraining dark energy
• Entropy of universe as entanglement entropy
• Axion excursions of the landscape during inflation
• Aligned Natural Inflation in the Large Volume Scenario
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• On the Scale of New Physics in Inflation
• Divisor topologies of CICY 3-folds and their applications to phenomenology