Universality Classes of Scale Invariant Inflation

Mehmet Ozkan, Diederik Roest

Research output: Working paperAcademic

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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.
Original languageEnglish
Publication statusPublished - 13-Jul-2015


  • hep-th
  • astro-ph.CO
  • gr-qc


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