Gravitational waves and the scale of inflation

2014/12/31 by Mehrdad Mirbabayi, Leonardo Senatore, Eva Silverstein +2 · 5 citations
Earth and Planetary Sciences · Mathematics · Physics and Astronomy · #Cosmology and Gravitation Theories #Geometry #Geophysics and Gravity Measurements #Gravitation #Gravitational wave #Inflation (cosmology) #Inflaton #Mathematical physics #Mathematics #Physics #Quantum mechanics #Scalar (mathematics) #Solar and Space Plasma Dynamics #Tensor (intrinsic definition) #astro-ph.CO #hep-th

paper · pdf · doi:10.1103/physrevd.91.063518

published as Phys. Rev. D 91, 063518 (2015) · 12 pages

openalex publication_date 2015/03/12 · arxiv created 2015/04/17 · arxiv updated 2015/04/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We revisit alternative mechanisms of gravitational wave production during inflation and argue that they generically emit a non-negligible amount of scalar fluctuations. We find the scalar power is larger than the tensor power by a factor of order 1/\ensuremathε². For an appreciable tensor contribution, the associated scalar emission completely dominates the zero-point fluctuations of the inflaton, resulting in a tensor-to-scalar ratio r\ensuremath∼\ensuremathε². A more quantitative result can be obtained if one further assumes that gravitational waves are emitted by localized subhorizon processes, giving r_max\ensuremath≃0.3\ensuremathε². However, \ensuremathε is generally time dependent, and this result for r depends on its instantaneous value during the production of the sources, rather than just its average value, somewhat relaxing constraints from the tilt n_s. We calculate the scalar 3-point correlation function in the same class of models and show that non-Gaussianity cannot be made arbitrarily small, i.e. f_NL\ensuremath\gtrsim1, independently of the value of r. Possible exceptions in multifield scenarios are discussed.

Citations

• A General Analytic Formula for the Spectral Index of the Density Perturbations produced during Inflation
• Inflation Physics from the Cosmic Microwave Background and Large Scale Structure
• Statistics of cosmic microwave background polarization

Cited by

• Observable chiral gravitational waves from inflation in string theory
• Probing the inflationary background of gravitational waves from large to small scales
• Gravitational waves in bouncing cosmologies from gauge field production
• Tensor squeezed limits and the Higuchi bound
• Rolling axions during inflation: perturbativity and signatures