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Title: Fermionic isocurvature perturbations

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 91; Journal Issue: 4; Related Information: CHORUS Timestamp: 2017-06-23 01:21:43; Journal ID: ISSN 1550-7998
American Physical Society
Country of Publication:
United States

Citation Formats

Chung, Daniel J. H., Yoo, Hojin, and Zhou, Peng. Fermionic isocurvature perturbations. United States: N. p., 2015. Web. doi:10.1103/PhysRevD.91.043516.
Chung, Daniel J. H., Yoo, Hojin, & Zhou, Peng. Fermionic isocurvature perturbations. United States. doi:10.1103/PhysRevD.91.043516.
Chung, Daniel J. H., Yoo, Hojin, and Zhou, Peng. Wed . "Fermionic isocurvature perturbations". United States. doi:10.1103/PhysRevD.91.043516.
title = {Fermionic isocurvature perturbations},
author = {Chung, Daniel J. H. and Yoo, Hojin and Zhou, Peng},
abstractNote = {},
doi = {10.1103/PhysRevD.91.043516},
journal = {Physical Review D},
number = 4,
volume = 91,
place = {United States},
year = {Wed Feb 11 00:00:00 EST 2015},
month = {Wed Feb 11 00:00:00 EST 2015}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevD.91.043516

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Cited by: 8works
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  • It has been observed that if an extra scalar field (in addition to the inflaton) is present during the inflationary phase, its decay into thermal radiation after baryogenesis gives rise to fluctuations in the initially smooth entropy-per-baryon ratio. There was a hope that these perturbations were of the isocurvature type and that they may help explain several observed features in the large-scale structure of the Universe. We study in detail the generation of perturbations in such a two-field inflationary model. We find that the resulting fluctuations are not of the isocurvature type, but that the entropy perturbation induces a curvaturemore » fluctuation which is larger than the entropic one before the wavelengths of the perturbations enter the Hubble radius. Thus, this model is not a good candidate to provide the initial conditions for the baryon isocurvature perturbations.« less
  • The dynamics of long-wave isocurvature perturbations during an inflationary stage in multiple (multicomponent) inflationary models is calculated analytically for the case where scalar fields producing this stage interact among themselves through gravity only. This enables us to determine the correct amplitudes of such perturbations produced by vacuum quantum fluctuations of the scalar fields during the multiple inflationary stage. An exact matching to a post-inflationary evolution that gives the amplitude of isocurvature perturbations in the cold dark matter model with radiation is performed in the case where a massive inflaton field remains uncoupled from usual matter up to the present time.more » For this model, isocurvature perturbations are smaller than adiabatic ones in the region of the break in the perturbation spectrum which arises due to a transition between the two phases of inflation, but they may be much bigger and have a maximum at much shorter scales. The case of an inflaton with a quartic coupling that remains uncoupled after inflation is considered, too.« less
  • We present a class of very simple inflationary models of two scalar fields which leads to non-Gaussian isothermal perturbations with a {open_quotes}blue{close_quotes} spectrum, n{gt}1. One of the models is inspired by supersymmetric theories where light scalar fields naturally acquire masses {approximately}H during inflation. Another model presumes that one of the fields has a nonminimal interaction with gravity {xi}R{sigma}{sup 2}. By a slight modification of parameters of these models one can obtain either Gaussian isothermal perturbations, or non-Gaussian adiabatic perturbations with n{gt}1. {copyright} {ital 1997} {ital The American Physical Society}
  • We investigate non-Gaussian isocurvature perturbations generated by the evolution of Goldstone modes during inflation. If a global symmetry is broken {ital before} inflation, the resulting Goldstone modes are disordered during inflation in a precise and predictable way. After inflation these Goldstone modes order themselves in a self-similar way, much as Goldstone modes in field ordering scenarios based on the Kibble mechanism. For (H{sub inf}{sup 2}/M{sub Pl}{sup 2}){approximately}10{sup {minus}6}, through their gravitational interaction these Goldstone modes generate density perturbations of approximately the right magnitude to explain the cosmic microwave background (CMB) anisotropy and seed the structure seen in the universe today.more » We point out that for the pattern of symmetry breaking in which a global U(1) is completely broken, the inflationary evolution of the Goldstone field may be treated as that of a massless scalar field. Unlike the more commonly discussed case in which a global U(1) is completely broken in a cosmological phase transition, in the inflationary case the production of defects can be made exponentially small, so that Goldstone field evolution is completely linear. In such a model non-Gaussian perturbations result because to lowest order density perturbations are sourced by products of Gaussian fields. Consequently, in this non-Gaussian model N-point correlations may be calculated by evaluating Feynman diagrams. We explore the issue of phase dispersion and conclude that this non-Gaussian model predicts Doppler peaks in the CMB anisotropy. {copyright} {ital 1997} {ital The American Physical Society}« less
  • Density perturbations in a universe in which matter consists of noninteracting nonrelativistic particles(dust) and strongly coupled photon-baryon fluid(radiation) are analyzed in terms of the gauge-invariant formalism extended to a multi-component system. Detailed analytic estimate is presented for the time evolution of both primordially adiabatic and primordially isocurvature perturbations. In particular, analytic formulas for characteristic scales appearing in the transfer functions are derived. The evolutionary behavior of these two types of perturbations are compared and the origins of their differences and similarities are clarified.