Large Field Inflation and Gravitational Entropy

Abstract

Large field inflation can be sensitive to perturbative and nonperturbative quantum corrections that spoil slow roll. A large number $N$ of light species in the theory, which occur in many string constructions, can amplify these problems. One might even worry that in a de Sitter background, light species will lead to a violation of the covariant entropy bound at large $N$. If so, requiring the validity of the covariant entropy bound could limit the number of light species and their couplings, which in turn could severely constrain axion-driven inflation. Here we show that there is no such problem when we correctly renormalize models with many light species, taking the {\it physical} Planck scale to be $M_{pl}^2\gtrsim N{\mathcal{M}}_{UV}^2$, where ${\mathcal{M}}_{UV}$ is the cutoff for the QFT coupled to semiclassical quantum gravity. The number of light species then cancels out of the gravitational entropy of de Sitter or near-de Sitter backgrounds at leading order. Working in detail with $N$ scalar fields in de Sitter space, renormalized to one loop order, we show that the gravitational entropy automatically obeys the covariant entropy bound. Furthermore, while the axion decay constant is a strong coupling scale for the axion dynamics, we show that it is {\it not} in general the cutoff of 4d semiclassical gravity. After renormalizing the two point function of the inflaton, we note that it is also controlled by scales much below the cutoff. We revisit $N$-flation and KKLT-type compactifications in this light, and show that they are perfectly consistent with the covariant entropy bound. Thus, while quantum gravity might yet spoil large field inflation, holographic considerations in the semiclassical theory do not obstruct it.

25 pages including references and title page, 18 pages of text. v2: References added, corrected argument at end of Sec. 2.3, additional minor corrections. v3: additional references added

References in corpus (72)

• A Large Mass Hierarchy from a Small Extra Dimension
• An Alternative to Compactification
• de Sitter Vacua in String Theory
• Thermalization and its mechanism for generic isolated quantum systems
• The String Landscape, Black Holes and Gravity as the Weakest Force
• Quantum Contributions to Cosmological Correlations
• Monodromy in the CMB: Gravity Waves and String Inflation
• A Covariant Entropy Conjecture
• Gravity Waves and Linear Inflation from Axion Monodromy
• Completing Natural Inflation
• N-flation
• AdS/CFT and gravity
• From Quantum Dynamics to the Canonical Distribution: General Picture and a Rigorous Example
• Holography and Compactification
• Black Holes and Large N Species Solution to the Hierarchy Problem
• A Natural Framework for Chaotic Inflation
• Remarks on entanglement entropy for gauge fields
• Black Hole Bound on the Number of Species and Quantum Gravity at LHC
• Racetrack Inflation
• Decomposition of entanglement entropy in lattice gauge theory
• An Ignoble Approach to Large Field Inflation
• Signatures of Short Distance Physics in the Cosmic Microwave Background
• Extranatural Inflation
• On Loops in Inflation
• DeSitter entropy, quantum entanglement and ADS/CFT
• Transplanckian axions !?
• On The Entanglement Entropy For Gauge Theories
• Semiclassical relations and IR effects in de Sitter and slow-roll space-times
• Entanglement entropy in de Sitter space
• Sequestering the Standard Model Vacuum Energy
• F-term Axion Monodromy Inflation
• Natural Inflation and Quantum Gravity
• Geometric entropy and edge modes of the electromagnetic field
• Planckian Axions and the Weak Gravity Conjecture
• D7-Brane Chaotic Inflation
• Aspects of Entanglement Entropy for Gauge Theories
• Towards Universal Axion Inflation and Reheating in String Theory
• Black hole entropy as entanglement entropy: a holographic derivation
• Pseudonatural Inflation
• Large-N bounds on, and compositeness limit of, gauge and gravitational interactions
• Weak Gravity Strongly Constrains Large-Field Axion Inflation
• On the Possibility of Large Axion Moduli Spaces
• Dante's Inferno
• A Manifestly Local Theory of Vacuum Energy Sequestering
• On Axionic Field Ranges, Loopholes and the Weak Gravity Conjecture
• Vacuum Energy Sequestering: The Framework and Its Cosmological Consequences
• Warping the Weak Gravity Conjecture
• The Challenge of Realizing F-term Axion Monodromy Inflation in String Theory
• Minkowski 3-forms, Flux String Vacua, Axion Stability and Naturalness
• The Lyth Bound Revisited
• Higgs-otic Inflation and String Theory
• The Inflaton as a MSSM Higgs and Open String Modulus Monodromy Inflation
• Planckian Axions in String Theory
• Towards large r from [p,q]-inflation
• Unwinding Inflation
• Renormalization of Entanglement Entropy and the Gravitational Effective Action
• Axion Inflation in F-theory
• Bounds on Generic High-Energy Physics Modifications to the Primordial Power Spectrum from Back-Reaction on the Metric
• Entropy of 2+1 dimensional de Sitter space in terms of brick wall method
• Quantum Gravity Constraints on Inflation
• Combining Universal and Odd RR Axions for Aligned Natural Inflation
• Holographic bounds on the UV cutoff scale in inflationary cosmology
• Black hole entanglement entropy and the renormalization group
• Black Hole Entropy and Gravity Cutoff
• Renormalization group flow of entanglement entropy on spheres
• Large-scale anomalies from primordial dissipation
• Newton constant, contact terms and entropy
• Inflation from Flux Cascades
• Observational Implications of Cosmological Event Horizons
• Multifield Dynamics in Higgs-otic Inflation
• An upper bound on the number of e-foldings
• Cutoffs, Stretched Horizons and Black Hole Radiators

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