Decoupling survives inflation: A critical look at effective field theory violations during inflation

Anastasios Avgoustidis, Sera Cremonini, Anne Christine Davis, Raquel H. Ribeiro, Krzysztof Turzyski, Scott Watson

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


We investigate the validity of effective field theory methods and the decoupling of heavy fields during inflation. Considering models of inflation in which the inflaton is coupled to a heavy (super-Hubble) degree of freedom initially in its vacuum state, we find that violations of decoupling are absent unless there is a breakdown of the slow-roll conditions. Next we allow for a temporary departure from inflation resulting in a period of non-adiabaticity during which effective field theory methods are known to fail. We find that the locality of the event and energy conservation lead to a tight bound on the size of the effects of the heavy field. We discuss the implications for the power spectrum and non-gaussianity, and comment on the connection with recent studies of the dynamics of multi-field inflation models. Our results further motivate the use of effective field theory methods to characterize cosmic inflation, and focus the question of observability of additional degrees of freedom during inflation to near the Hubble scale or below - as anticipated from the Wilsonian notions of decoupling and naturalness.

Original languageEnglish (US)
Article number025
JournalJournal of Cosmology and Astroparticle Physics
Issue number6
StatePublished - Jun 2012


  • cosmological perturbation theory
  • ination

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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