Inflation in Motion: Unitarity Constraints in Effective Field Theories with Broken Lorentz Symmetry

Abstract

During inflation, there is a preferred reference frame in which the expansion of the background spacetime is spatially isotropic. In contrast to Minkowski spacetime, observables can depend on the velocity of the system with respect to this cosmic rest frame. We derive new constraints from radiative stability and unitarity on effective field theories with such spontaneously broken Lorentz symmetry. In addition to a maximum energy scale, there is now also a critical velocity at which the theory breaks down. The theory therefore has different resolving power in time and in space, and we show that these can only coincide if cubic Lorentz-violating interactions are absent. Applying these bounds to the Effective Field Theory of Inflation, we identify the region of parameter space in which inflation can be both single-field and weakly coupled on subhorizon scales. This can be implemented as a theoretical prior, and we illustrate this explicitly using Planck observational constraints on the primordial bispectrum.

arXiv comment41 pages plus Appendices, 7 figures (replaced to match journal version. [55] refers to 2102.05683)

References in corpus (38)

• Lorentz-Violating Extension of the Standard Model
• Gravity, Lorentz Violation, and the Standard Model
• The Effective Field Theory of Inflation
• Causality, Analyticity and an IR Obstruction to UV Completion
• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• Quantum Time Crystals
• The Strongly-Interacting Light Higgs
• Starting the Universe: Stable Violation of the Null Energy Condition and Non-standard Cosmologies
• Stability, Causality, and Lorentz and CPT Violation
• The Effective Field Theory of Dark Energy
• On graviton non-Gaussianities during inflation
• Classical Time Crystals
• Introduction to Effective Field Theory
• On the consistency relation of the 3-point function in single field inflation
• Equilateral Non-Gaussianity and New Physics on the Horizon
• Counting 4 pi 's in Strongly Coupled Supersymmetry
• New Recursion Relations and a Flat Space Limit for AdS/CFT Correlators
• The Inflationary Trispectrum for Models with Large Non-Gaussianities
• Effective Field Theory of Cosmological Perturbations
• Signs of Analyticity in Single-Field Inflation
• On the Power Counting in Effective Field Theories
• Large non-Gaussianities in the Effective Field Theory Approach to Single-Field Inflation: the Trispectrum
• Simple Bounds from the Perturbative Regime of Inflation
• Naive Dimensional Analysis Counting of Gauge Theory Amplitudes and Anomalous Dimensions
• Effective field theory of weakly coupled inflationary models
• Planck-Suppressed Operators
• B-modes and the Nature of Inflation
• Aspects of Galileon Non-Renormalization
• The Conformal Limit of Inflation in the Era of CMB Polarimetry
• Unitary null energy condition violation in $P(X)$ cosmologies
• Bounds on non-adiabatic evolution in single-field inflation
• On the integration of fields and quanta in time dependent backgrounds
• The structure of correlation functions in single field inflation
• Power-counting during single-field slow-roll inflation
• Perturbative Unitarity of Inflationary Models with Features
• Boost Breaking in the EFT of Inflation
• Where does Cosmological Perturbation Theory Break Down?
• Keeping an Eye on DBI: Power-counting for small-$c_s$ Cosmology

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• From Amplitudes to Contact Cosmological Correlators
• Amplitudes meet Cosmology: A (Scalar) Primer
• A Differential Representation of Cosmological Wavefunctions
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• The Open Effective Field Theory of Inflation
• The Cosmological Phonon: Symmetries and Amplitudes on Sub-Horizon Scales
• Positivity bounds from multiple vacua and their cosmological consequences
• Large Deviations in the Early Universe
• Scalar Fields Near Compact Objects: Resummation versus UV Completion
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• Perturbative unitarity and NEC violation in genesis cosmology
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• Cosmological cutting rules for Bogoliubov initial states
• Perturbative unitarity bounds from momentum-space entanglement
• The Massive Flat Space Limit of Cosmological Correlators
• Bispectrum Islands
• Perturbative unitarity bounds on field-space curvature in de Sitter spacetime: purity vs scattering amplitude
• Propagator positivity bounds for cosmological correlators
• A Tail of Eternal Inflation