The spectral index and its running in axionic curvaton

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16 Citations (Scopus)

Abstract

We show that a sizable running spectral index suggested by the recent SPT data can be explained in the axionic curvaton model with a potential that consists of two sinusoidal contributions of different height and period. We find that the running spectral index is generically given by dns/d ln k ∼ 2π/ΔN (ns - 1)) where ΔN is the e-folds during one period of modulations. In the string axiverse, axions naturally acquire a mass from multiple contributions, and one of the axions may be responsible for the density perturbations with a sizable running spectral index via the curvaton mechanism. We note that the axionic curvaton model with modulations can also accommodate the red-tilted spectrum with a negligible running, without relying on large-field inflation.

Original languageEnglish
Article number013
JournalJournal of Cosmology and Astroparticle Physics
Volume2013
Issue number6
DOIs
Publication statusPublished - 2013 Jun

Keywords

  • Cosmological parameters from CMBR
  • Cosmological perturbation theory
  • Cosmology of theories beyond the SM
  • Physics of the early universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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