Resilience of the standard predictions for primordial tensor modes

Abstract

We show that the prediction for the primordial tensor power spectrum cannot be modified at leading order in derivatives. Indeed, one can always set to unity the speed of propagation of gravitational waves during inflation by a suitable disformal transformation of the metric, while a conformal one can make the Planck mass time-independent. Therefore, the tensor amplitude unambiguously fixes the energy scale of inflation. Using the Effective Field Theory of Inflation, we check that predictions are independent of the choice of frame, as expected. The first corrections to the standard prediction come from two parity violating operators with three derivatives. Also the correlator $<\gamma \gamma \gamma >$ is standard and only receives higher derivative corrections. These results hold also in multifield models of inflation and in alternatives to inflation and make the connection between a (quasi) scale-invariant tensor spectrum and inflation completely robust.

5 pages, reference added, version accepted in PRL

References in corpus (6)

• The Effective Field Theory of Inflation
• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• Starting the Universe: Stable Violation of the Null Energy Condition and Non-standard Cosmologies
• Galilean Genesis: an alternative to inflation
• Chiral Primordial Gravitational Waves from a Lifshitz Point
• Detecting chiral gravity with the pure pseudospectrum reconstruction of the cosmic microwave background polarized anisotropies

Cited by in corpus (53)

• Horndeski theory and beyond: a review
• Science with the space-based interferometer LISA. IV: Probing inflation with gravitational waves
• Non-Gaussianity as a Particle Detector
• Parity breaking signatures from a Chern-Simons coupling during inflation: the case of non-Gaussian gravitational waves
• Stability of Geodesically Complete Cosmologies
• Disformal couplings and the dark sector of the universe
• Measuring the speed of cosmological gravitational waves
• Generalised tensor fluctuations and inflation
• Parity violation in the scalar trispectrum: no-go theorems and yes-go examples
• Measuring Parity Violation in the Stochastic Gravitational Wave Background with the LISA-Taiji network
• Bootstrapping Large Graviton non-Gaussianities
• Gravitational Waves and the Scale of Inflation
• Tests of Gravitational-Wave Birefringence with the Open Gravitational-Wave Catalog
• Gravitational Waves and Scalar Perturbations from Spectator Fields
• Inflation from Minkowski Space
• Measuring the propagation speed of gravitational waves with LISA
• The graviton four-point function in de Sitter space
• Disformal invariance of cosmological perturbations in a generalized class of Horndeski theories
• Towards a reliable calculation of relic radiation from primordial gravitational waves
• Gaugid inflation
• On Graviton non-Gaussianities in the Effective Field Theory of Inflation
• Higher-Curvature Corrections and Tensor Modes
• Simplifying the EFT of Inflation: Generalized Disformal Transformations and Redundant Couplings
• The effective theory of fluids at NLO and implications for dark energy
• Nanohertz gravitational waves from NEC violation in the early universe
• Generating enhanced primordial GWs during inflation with intermittent violation of NEC and diminishment of GW propagating speed
• Oscillating modulation to B-mode polarization from varying propagating speed of primordial gravitational waves
• There and Back Again: Mapping and Factorising Cosmological Observables
• Scale-invariant perturbations from NEC violation: A new variant of Galilean Genesis
• Generalized non-local $R^2$-like inflation
• Inflationary gravitational waves in the effective field theory of modified gravity
• Induced geometry from disformal transformation
• Scalar-Induced Gravitational Waves from Ghost Inflation and Parity Violation
• Revisiting slow-roll dynamics and the tensor tilt in general single-field inflation
• The mirage of luminal modified gravitational-wave propagation
• Primordial Gravitational Waves Assisted by Cosmological Scalar Perturbations
• Mixed Graviton and Scalar Bispectra in the EFT of Inflation: Soft Limits and Boostless Bootstrap
• Parametric resonance of gravitational waves in general scalar-tensor theories
• The Cosmological OTOC: A New Proposal for Quantifying Auto-Correlated Random Non-Chaotic Primordial Fluctuations
• Quantum gravity phenomenology at the dawn of the multi-messenger era -- A review
• Chiral primordial gravitational waves in extended theories of Scalar-Tensor gravity
• Effective speed of gravitational waves
• Extracting parity-violating gravitational waves from projected tidal force tensor in three dimensions
• Effective Field Theory of Chiral Gravitational Waves
• Non-Gaussianities in generalized non-local $R^2$-like inflation
• Potential-driven Inflation with Disformal Coupling to Gravity
• Disformal invariance of continuous media with linear equation of state
• Gravitoelectromagnetic quadrirefringence
• Constraining the effective field theory of dark energy with multimessenger astronomy
• Multimodality in the Search for New Physics in Pulsar Timing Data and the Case of Kination-amplified Gravitational-wave Background from Inflation
• Effective speed of cosmological perturbations
• A Match Made in Heaven: Linking Observables in Inflationary Cosmology
• Weakly Broken Galileon Symmetry in Cosmology