Parity breaking signatures from a ChernSimons coupling during inflation: the case of nonGaussian gravitational waves
Abstract
Considering highenergy modifications of Einstein gravity during inflation is an interesting issue. We can constrain the strength of the new gravitational terms through observations of inflationary imprints in the actual universe. In this paper we analyze the effects on slowroll models due to a ChernSimons term coupled to the inflaton field through a generic coupling function f (φ). A well known result is the polarization of primordial gravitational waves (PGW) into left and right eigenstates, as a consequence of parity breaking. In such a scenario the modifications to the power spectrum of PGW are suppressed under the conditions that allow to avoid the production of ghost gravitons at a certain energy scale, the socalled ChernSimons mass M {sub CS}. In general it has been recently pointed out that there is very little hope to efficiently constrain chirality of PGW on the basis solely of twopoint statistics from future CMB data, even in the most optimistic cases. Thus we search if significant parity breaking signatures can arise at least in the bispectrum statistics. We find that the tensortensorscalar bispectra ( γ γ ζ ) for each polarization state are the only ones that are not suppressed. Their amplitude, setting the levelmore »
 Authors:
 Dipartimento di Fisica e Astronomia ''G. Galilei', Università degli Studi di Padova, via Marzolo 8, 35131, Padova (Italy)
 Publication Date:
 OSTI Identifier:
 22676095
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 07; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHIRALITY; COUPLING; EIGENSTATES; GENERAL RELATIVITY THEORY; GRAVITATIONAL WAVES; GRAVITONS; INFLATIONARY UNIVERSE; INFLATONS; MASS; MODIFICATIONS; PARITY; POLARIZATION; RELICT RADIATION; SPECTRA; STATISTICS; UNIVERSE
Citation Formats
Bartolo, Nicola, and Orlando, Giorgio, Email: nicola.bartolo@pd.infn.it, Email: giorgio.orlando@phd.unipd.it. Parity breaking signatures from a ChernSimons coupling during inflation: the case of nonGaussian gravitational waves. United States: N. p., 2017.
Web. doi:10.1088/14757516/2017/07/034.
Bartolo, Nicola, & Orlando, Giorgio, Email: nicola.bartolo@pd.infn.it, Email: giorgio.orlando@phd.unipd.it. Parity breaking signatures from a ChernSimons coupling during inflation: the case of nonGaussian gravitational waves. United States. doi:10.1088/14757516/2017/07/034.
Bartolo, Nicola, and Orlando, Giorgio, Email: nicola.bartolo@pd.infn.it, Email: giorgio.orlando@phd.unipd.it. Sat .
"Parity breaking signatures from a ChernSimons coupling during inflation: the case of nonGaussian gravitational waves". United States.
doi:10.1088/14757516/2017/07/034.
@article{osti_22676095,
title = {Parity breaking signatures from a ChernSimons coupling during inflation: the case of nonGaussian gravitational waves},
author = {Bartolo, Nicola and Orlando, Giorgio, Email: nicola.bartolo@pd.infn.it, Email: giorgio.orlando@phd.unipd.it},
abstractNote = {Considering highenergy modifications of Einstein gravity during inflation is an interesting issue. We can constrain the strength of the new gravitational terms through observations of inflationary imprints in the actual universe. In this paper we analyze the effects on slowroll models due to a ChernSimons term coupled to the inflaton field through a generic coupling function f (φ). A well known result is the polarization of primordial gravitational waves (PGW) into left and right eigenstates, as a consequence of parity breaking. In such a scenario the modifications to the power spectrum of PGW are suppressed under the conditions that allow to avoid the production of ghost gravitons at a certain energy scale, the socalled ChernSimons mass M {sub CS}. In general it has been recently pointed out that there is very little hope to efficiently constrain chirality of PGW on the basis solely of twopoint statistics from future CMB data, even in the most optimistic cases. Thus we search if significant parity breaking signatures can arise at least in the bispectrum statistics. We find that the tensortensorscalar bispectra ( γ γ ζ ) for each polarization state are the only ones that are not suppressed. Their amplitude, setting the level of parity breaking during inflation, is proportional to the second derivative of the coupling function f (φ) and they turn out to be maximum in the squeezed limit. We comment on the squeezedlimit consistency relation arising in the case of chiral gravitational waves, and on possible observables to constrain these signatures.},
doi = {10.1088/14757516/2017/07/034},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 07,
volume = 2017,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}

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