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Title: Anisotropic power spectrum and bispectrum in the f(Φ)F² mechanism

Abstract

A suitable coupling of the inflaton φ to a vector kinetic term F² gives frozen and scale invariant vector perturbations. We compute the cosmological perturbations ζ that result from such coupling by taking into account the classical vector field that unavoidably gets generated at large scales during inflation. This generically results in a too-anisotropic power spectrum of ζ. Specifically, the anisotropy exceeds the 1% level (10% level) if inflation lasts ~5 e-folds (~50 e-folds) more than the minimal amount required to produce the cosmic microwave background modes. This conclusion applies, among others, to the application of this mechanism for magnetogenesis, for anisotropic inflation, and for the generation of anisotropic perturbations at the end of inflation through a waterfall field coupled to the vector (in this case, the unavoidable contribution that we obtain is effective all throughout inflation, and it is independent of the waterfall field). For a tuned duration of inflation, a 1% (10%) anisotropy in the power spectrum corresponds to an anisotropic bispectrum which is enhanced like the local one in the squeezed limit, and with an effective local f NL~3(~30). More in general, a significant anisotropy of the perturbations may be a natural outcome of all models thatmore » sustain higher than 0 spin fields during inflation.« less

Authors:
; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1102652
Resource Type:
Publisher's Accepted Manuscript
Journal Name:
Physical Review. D, Particles, Fields, Gravitation and Cosmology
Additional Journal Information:
Journal Name: Physical Review. D, Particles, Fields, Gravitation and Cosmology Journal Volume: 87 Journal Issue: 2; Journal ID: ISSN 1550-7998
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Bartolo, Nicola, Matarrese, Sabino, Peloso, Marco, and Ricciardone, Angelo. Anisotropic power spectrum and bispectrum in the f(Φ)F² mechanism. United States: N. p., 2013. Web. doi:10.1103/PhysRevD.87.023504.
Bartolo, Nicola, Matarrese, Sabino, Peloso, Marco, & Ricciardone, Angelo. Anisotropic power spectrum and bispectrum in the f(Φ)F² mechanism. United States. doi:10.1103/PhysRevD.87.023504.
Bartolo, Nicola, Matarrese, Sabino, Peloso, Marco, and Ricciardone, Angelo. Fri . "Anisotropic power spectrum and bispectrum in the f(Φ)F² mechanism". United States. doi:10.1103/PhysRevD.87.023504.
@article{osti_1102652,
title = {Anisotropic power spectrum and bispectrum in the f(Φ)F² mechanism},
author = {Bartolo, Nicola and Matarrese, Sabino and Peloso, Marco and Ricciardone, Angelo},
abstractNote = {A suitable coupling of the inflaton φ to a vector kinetic term F² gives frozen and scale invariant vector perturbations. We compute the cosmological perturbations ζ that result from such coupling by taking into account the classical vector field that unavoidably gets generated at large scales during inflation. This generically results in a too-anisotropic power spectrum of ζ. Specifically, the anisotropy exceeds the 1% level (10% level) if inflation lasts ~5 e-folds (~50 e-folds) more than the minimal amount required to produce the cosmic microwave background modes. This conclusion applies, among others, to the application of this mechanism for magnetogenesis, for anisotropic inflation, and for the generation of anisotropic perturbations at the end of inflation through a waterfall field coupled to the vector (in this case, the unavoidable contribution that we obtain is effective all throughout inflation, and it is independent of the waterfall field). For a tuned duration of inflation, a 1% (10%) anisotropy in the power spectrum corresponds to an anisotropic bispectrum which is enhanced like the local one in the squeezed limit, and with an effective local fNL~3(~30). More in general, a significant anisotropy of the perturbations may be a natural outcome of all models that sustain higher than 0 spin fields during inflation.},
doi = {10.1103/PhysRevD.87.023504},
journal = {Physical Review. D, Particles, Fields, Gravitation and Cosmology},
number = 2,
volume = 87,
place = {United States},
year = {2013},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1103/PhysRevD.87.023504

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