Planck limits on noncanonical generalizations of largefield inflation models
Abstract
In this paper, we consider two case examples of DiracBornInfeld (DBI) generalizations of canonical largefield inflation models, characterized by a reduced sound speed, c {sub S} < 1. The reduced speed of sound lowers the tensorscalar ratio, improving the fit of the models to the data, but increases the equilateralmode nonGaussianity, f {sup equil.}{sub NL}, which the latest results from the Planck satellite constrain by a new upper bound. We examine constraints on these models in light of the most recent Planck and BICEP/Keck results, and find that they have a greatly decreased window of viability. The upper bound on f {sup equil.}{sub NL} corresponds to a lower bound on the sound speed and a corresponding lower bound on the tensorscalar ratio of r ∼ 0.01, so that nearfuture Cosmic Microwave Background observations may be capable of ruling out entire classes of DBI inflation models. The result is, however, not universal: infraredtype DBI inflation models, where the speed of sound increases with time, are not subject to the bound.
 Authors:
 Dept. of Physics, University at Buffalo, the State University of New York, Buffalo, NY 142601500 (United States)
 Publication Date:
 OSTI Identifier:
 22679937
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 04; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BORNINFELD THEORY; INFLATIONARY UNIVERSE; RELICT RADIATION; SATELLITES; SOUND WAVES; VELOCITY; VISIBLE RADIATION
Citation Formats
Stein, Nina K., and Kinney, William H., Email: ninastei@buffalo.edu, Email: whkinney@buffalo.edu. Planck limits on noncanonical generalizations of largefield inflation models. United States: N. p., 2017.
Web. doi:10.1088/14757516/2017/04/006.
Stein, Nina K., & Kinney, William H., Email: ninastei@buffalo.edu, Email: whkinney@buffalo.edu. Planck limits on noncanonical generalizations of largefield inflation models. United States. doi:10.1088/14757516/2017/04/006.
Stein, Nina K., and Kinney, William H., Email: ninastei@buffalo.edu, Email: whkinney@buffalo.edu. Sat .
"Planck limits on noncanonical generalizations of largefield inflation models". United States.
doi:10.1088/14757516/2017/04/006.
@article{osti_22679937,
title = {Planck limits on noncanonical generalizations of largefield inflation models},
author = {Stein, Nina K. and Kinney, William H., Email: ninastei@buffalo.edu, Email: whkinney@buffalo.edu},
abstractNote = {In this paper, we consider two case examples of DiracBornInfeld (DBI) generalizations of canonical largefield inflation models, characterized by a reduced sound speed, c {sub S} < 1. The reduced speed of sound lowers the tensorscalar ratio, improving the fit of the models to the data, but increases the equilateralmode nonGaussianity, f {sup equil.}{sub NL}, which the latest results from the Planck satellite constrain by a new upper bound. We examine constraints on these models in light of the most recent Planck and BICEP/Keck results, and find that they have a greatly decreased window of viability. The upper bound on f {sup equil.}{sub NL} corresponds to a lower bound on the sound speed and a corresponding lower bound on the tensorscalar ratio of r ∼ 0.01, so that nearfuture Cosmic Microwave Background observations may be capable of ruling out entire classes of DBI inflation models. The result is, however, not universal: infraredtype DBI inflation models, where the speed of sound increases with time, are not subject to the bound.},
doi = {10.1088/14757516/2017/04/006},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 04,
volume = 2017,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}

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