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Title: The curvature perturbation in the axion-type curvaton model

Abstract

We study the axion-type curvaton model, with emphasis on the large field regime where analytic results are very difficult to obtain. We evaluate the tensor-scalar ratio r using WMAP normalization and the non-linearity parameters f{sub NL} and g{sub NL} by solving the equations numerically using the {delta}N formalism. We compare them with results for the curvaton with quadratic potential. We find that r is much smaller for the axion-type case compared to the result from the quadratic potential, with the difference increasingly more pronounced at larger field values. g{sub NL} is found to be positive, unlike the quadratic case where it is negative, and the amplitude of g{sub NL} is much larger. Moreover, there is a nearly linear scaling between g{sub NL} and f{sub NL}, with small deviation from linearity at large field values. The slope between g{sub NL} and f{sub NL} depends on the parameters characterizing the axion-type curvaton model. We further consider a mixed scenario where both the inflaton and the curvaton contribute to the primordial power spectrum and the non-Gaussianity parameters are found to be much larger than those in the case with quadratic potential.

Authors:
;  [1]
  1. School of Physics, Korea Institute for Advanced Study, 207-43 Cheongryangri-2 Dong, Dongdaemun-Gu, Seoul 130-722 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22156981
Resource Type:
Journal Article
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2009; Journal Issue: 04; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; AXIONS; DISTURBANCES; NONLINEAR PROBLEMS; POTENTIALS; SCALARS; SCALING; SPECTRA; TENSORS

Citation Formats

Chingangbam, Pravabati, and Huang, Qing-Guo. The curvature perturbation in the axion-type curvaton model. United States: N. p., 2009. Web. doi:10.1088/1475-7516/2009/04/031.
Chingangbam, Pravabati, & Huang, Qing-Guo. The curvature perturbation in the axion-type curvaton model. United States. https://doi.org/10.1088/1475-7516/2009/04/031
Chingangbam, Pravabati, and Huang, Qing-Guo. Wed . "The curvature perturbation in the axion-type curvaton model". United States. https://doi.org/10.1088/1475-7516/2009/04/031.
@article{osti_22156981,
title = {The curvature perturbation in the axion-type curvaton model},
author = {Chingangbam, Pravabati and Huang, Qing-Guo},
abstractNote = {We study the axion-type curvaton model, with emphasis on the large field regime where analytic results are very difficult to obtain. We evaluate the tensor-scalar ratio r using WMAP normalization and the non-linearity parameters f{sub NL} and g{sub NL} by solving the equations numerically using the {delta}N formalism. We compare them with results for the curvaton with quadratic potential. We find that r is much smaller for the axion-type case compared to the result from the quadratic potential, with the difference increasingly more pronounced at larger field values. g{sub NL} is found to be positive, unlike the quadratic case where it is negative, and the amplitude of g{sub NL} is much larger. Moreover, there is a nearly linear scaling between g{sub NL} and f{sub NL}, with small deviation from linearity at large field values. The slope between g{sub NL} and f{sub NL} depends on the parameters characterizing the axion-type curvaton model. We further consider a mixed scenario where both the inflaton and the curvaton contribute to the primordial power spectrum and the non-Gaussianity parameters are found to be much larger than those in the case with quadratic potential.},
doi = {10.1088/1475-7516/2009/04/031},
url = {https://www.osti.gov/biblio/22156981}, journal = {Journal of Cosmology and Astroparticle Physics},
issn = {1475-7516},
number = 04,
volume = 2009,
place = {United States},
year = {2009},
month = {4}
}