Simple bounds from the perturbative regime of inflation

Louis Leblond, Sarah Shandera

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57 Scopus citations


We examine the conditions under which a perturbative expansion around an inflating background is valid. When inflation is driven by a single field with a general sound speed, we find a lower limit on the sound speed related to the amplitude of the inflationary power spectrum. Generalizing the sound speed constraints to include scale dependence can limit the number of e-folds obtained in the perturbative regime and restrict otherwise apparently viable models. We also show that, for models with a low sound speed, eternal inflation cannot occur in the perturbative regime.

Original languageEnglish (US)
Article number007
JournalJournal of Cosmology and Astroparticle Physics
Issue number8
StatePublished - Aug 1 2008

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics


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