The spectral index and its running in axionic curvaton

Journal Article · Sat Jun 01 04:00:00 EDT 2013 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2013/06/013· OSTI ID:22282903

Takahashi, Fuminobu ^[1]

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1. Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

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 dn{sub s}/dln k ∼ 2π/ΔN (n{sub s}−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.

• OSTI ID: 22282903
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 06 Vol. 2013; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGY
DENSITY
INFLATIONARY UNIVERSE
INFLATONS
MASS
MODULATION
PERTURBATION THEORY
POTENTIALS