Ultra slow-roll G inflation

2016/04/30 by Shin'ichi Hirano, Shin‐ichi Hirano, Tsutomu Kobayashi +1 · 4 citations
Mathematics · Physics and Astronomy · #Anisotropy #Astrophysics #Black Holes and Theoretical Physics #Classical mechanics #Cosmic background radiation #Cosmic microwave background #Cosmology and Gravitation Theories #Curvature #Galaxies: Formation, Evolution, Phenomena #Geometry #Hypersurface #Inflation (cosmology) #Inflaton #Kinetic energy #Mathematical analysis #Mathematical physics #Mathematics #Physics #Quantum mechanics #Scalar field #Slow roll #Spectral density #Theoretical physics #astro-ph.CO #gr-qc #hep-th

paper · pdf · doi:10.1103/physrevd.94.103515

published as Phys. Rev. D 94, 103515 (2016) · 9 pages, 6 figures; v2 is matched with the publication in PRD

openalex created_date 2016/06/24 · openalex publication_date 2016/11/16 · arxiv created 2016/11/17 · arxiv updated 2016/11/18 · openalex updated_date 2026/08/05

Abstract

The conventional slow-roll approximation is broken in the so-called ``ultra slow-roll'' models of inflation, for which the inflaton potential is exactly (or extremely) flat. The interesting nature of (canonical) ultra slow-roll inflation is that the curvature perturbation grows on superhorizon scales, but has a scale-invariant power spectrum. We study the ultra slow-roll inflationary dynamics in the presence of noncanonical kinetic terms of the scalar field, namely ultra slow-roll G inflation. We compute the evolution of the curvature perturbation and show that the primordial power spectrum follows a broken power law with an oscillation feature. It is demonstrated that this could explain the lack of large-scale power in the cosmic microwave background temperature anisotropies. We also point out that the violation of the null energy condition is prohibited in ultra slow-roll G inflation, and hence a blue tensor tilt is impossible as long as inflation is driven by the potential. This statement is, however, not true if the energy density is dominated by the kinetic energy of the scalar field.

Citations

• Suppressing the lower multipoles in the CMB anisotropies
• Violation of non-Gaussianity consistency relation in a single field inflationary model
• The development of irregularities in a single bubble inflationary universe
• Slow-roll inflation preceded by a topological defect phaseà laChaplygin gas
• Inflation model with lower multipoles of the CMB suppressed
• Non-Gaussian features of primordial fluctuations in single field inflationary models
• Dynamics of phase transition in the new inflationary universe scenario and generation of perturbations
• Second-order scalar-tensor field equations in a four-dimensional space
• Hidden negative energies in strongly accelerated universes
• Duality invariance of cosmological perturbation spectra
• Horizon crossing and inflation with largeη
• The galileon as a local modification of gravity
• Fluctuations in the New Inflationary Universe
• Generalized G-inflation: Inflation with the most general second-order field equations
• Planck 2015 results
• k-Inflation
• Planck 2015 results. XX. Constraints on inflation

Cited by

• Constant-Roll Inflation
• Constant-roll (quasi-)linear inflation
• Nonsingular cosmological models with strong gravity in the past
• Global adiabaticity and non-Gaussianity consistency condition