Universality Classes of Scale Invariant Inflation

Abstract

We investigate the inflationary implications of extensions of Poincare symmetry. The simplest constructions with local scale invariance lead to universal predictions: the spectral index is $n_s=1-2/N$, in excellent agreement with Planck data, while the tensor-to-scalar ratio is determined by a free parameter to $r=12\alpha /N^2$. For the special value $\alpha =1$ one finds symmetry enhancement to the full conformal group. We show that these findings hold both for two-derivative scalar-tensor theories as well as higher-derivative gravity. Therefore scale invariance underlies a promising set of inflationary models.

arXiv comment6 pages, 1 figure

References in corpus (14)

• Universality Class in Conformal Inflation
• Minimal Supergravity Models of Inflation
• The Unity of Cosmological Attractors
• A universal attractor for inflation at strong coupling
• Superconformal generalizations of the Starobinsky model
• Starobinsky-like Inflationary Models as Avatars of No-Scale Supergravity
• On the Starobinsky Model of Inflation from Supergravity
• Comments on the Starobinsky Model of Inflation and its Descendants
• Higher Order Corrections in Minimal Supergravity Models of Inflation
• Fake Conformal Symmetry in Conformal Cosmological Models
• Inflation from Broken Scale Invariance
• Inflation, Symmetry, and B-Modes
• Planck constraints on inflation in auxiliary vector modified $f(R)$ theories
• Gauge Natural Formulation of Conformal Theory of Gravity

Cited by in corpus (7)

• Spacetimes with vector distortion: Inflation from generalised Weyl geometry
• A frame independent classification of single field inflationary models
• Generalized Pole Inflation: Hilltop, Natural, and Chaotic Inflationary Attractors
• Transformations between Jordan and Einstein frames: Bounces, antigravity, and crossing singularities
• Natural Inflation with Hidden Scale Invariance
• Cosmology with vector distortion
• Broken scale invariance, $\alpha$-attractors and vector impurity