Running spectral index from inflation with modulations

Takeshi Kobayashi, Fuminobu Takahashi

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)


We argue that a large negative running spectral index, if confirmed, might suggest that there are abundant structures in the inflaton potential, which result in a fairly large (both positive and negative) running of the spectral index at all scales. It is shown that the center value of the running spectral index suggested by the recent CMB data can be easily explained by an inflaton potential with superimposed periodic oscillations. In contrast to cases with constant running, the perturbation spectrum is enhanced at small scales, due to the repeated modulations. We mention that such features at small scales may be seen by 21 cm observations in the future.

Original languageEnglish
Article number026
JournalJournal of Cosmology and Astroparticle Physics
Issue number1
Publication statusPublished - 2011 Jan


  • Cosmological parameters from CMBR
  • Inflation
  • Physics of the early universe
  • Power spectrum


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