Fine tuning and the ratio of tensor to scalar density fluctuations from cosmological inflation

Abstract

The form of the inflationary potential is severely restricted if one requires that it be natural in the technical sense, i.e. terms of unrelated origin are not required to be correlated. We determine the constraints on observables that are implied in such natural inflationary models, in particular on $r$, the ratio of tensor to scalar perturbations. We find that the naturalness constraint does not require $r$ to be lare enough to be detectable by the forthcoming searches for B-mode polarisation in CMB maps. We show also that the value of $r$ is a sensitive discriminator between inflationary models.

8 pages LaTeX; clarifications and a reference added; to appear in JCAP

References in corpus (5)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
• Monodromy in the CMB: Gravity Waves and String Inflation
• Inflation model constraints from the Wilkinson Microwave Anisotropy Probe three-year data
• Inflation models and observation
• Natural Inflation: the status after WMAP 3-year data

Cited by in corpus (13)

• Particle physics models of inflation and curvaton scenarios
• Generalized Uncertainty Principle: Approaches and Applications
• Observable gravitational waves from inflation with small field excursions
• Cosmic Microwave Background Observables of Small Field Models of Inflation
• An accurate bound on tensor-to-scalar ratio and the scale of inflation
• Minimal Inflation
• Reconstruction of the primordial power spectrum of curvature perturbations using multiple data sets
• A Minimal Inflation Scenario
• Hybrid natural inflation from non Abelian discrete symmetry
• Effects of quantum gravity on the inflationary parameters and thermodynamics of the early universe
• Hybrid Natural Low Scale Inflation
• Bound on largest $r\lesssim 0.1$ from sub-Planckian excursions of inflaton
• Primordial gravitational wave of BICEP2 from dynamical double hybrid inflation