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Title: Cumulative effects in inflation with ultra-light entropy modes

Abstract

In multi-field inflation one or more non-adiabatic modes may become light, potentially inducing large levels of isocurvature perturbations in the cosmic microwave background. If in addition these light modes are coupled to the adiabatic mode, they influence its evolution on super horizon scales. Here we consider the case in which a non-adiabatic mode becomes approximately massless (''ultralight') while still coupled to the adiabatic mode, a typical situation that arises with pseudo-Nambu-Goldstone bosons or moduli. This ultralight mode freezes on super-horizon scales and acts as a constant source for the curvature perturbation, making it grow linearly in time and effectively suppressing the isocurvature component. We identify a Stückelberg-like emergent shift symmetry that underlies this behavior. As inflation lasts for many e -folds, the integrated effect of this source enhances the power spectrum of the adiabatic mode, while keeping the non-adiabatic spectrum approximately untouched. In this case, towards the end of inflation all the fluctuations, adiabatic and non-adiabatic, are dominated by a single degree of freedom.

Authors:
;  [1];  [2];  [3]
  1. Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, 2333 CA Leiden (Netherlands)
  2. Institut de Ciéncies del Cosmos, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona (Spain)
  3. Grupo de Cosmología y Astrofísica Teórica, Departamento de Física, FCFM, Universidad de Chile, Blanco Encalada 2008, Santiago (Chile)
Publication Date:
OSTI Identifier:
22680042
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 02; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; DEGREES OF FREEDOM; DISTURBANCES; ENTROPY; EVOLUTION; FLUCTUATIONS; GOLDSTONE BOSONS; INFLATIONARY UNIVERSE; PERTURBATION THEORY; RELICT RADIATION; SPECTRA; SYMMETRY; VISIBLE RADIATION

Citation Formats

Achúcarro, Ana, Atal, Vicente, Germani, Cristiano, and Palma, Gonzalo A., E-mail: achucar@lorentz.leidenuniv.nl, E-mail: vicente.atal@icc.ub.edu, E-mail: germani@icc.ub.edu, E-mail: gpalmaquilod@ing.uchile.cl. Cumulative effects in inflation with ultra-light entropy modes. United States: N. p., 2017. Web. doi:10.1088/1475-7516/2017/02/013.
Achúcarro, Ana, Atal, Vicente, Germani, Cristiano, & Palma, Gonzalo A., E-mail: achucar@lorentz.leidenuniv.nl, E-mail: vicente.atal@icc.ub.edu, E-mail: germani@icc.ub.edu, E-mail: gpalmaquilod@ing.uchile.cl. Cumulative effects in inflation with ultra-light entropy modes. United States. doi:10.1088/1475-7516/2017/02/013.
Achúcarro, Ana, Atal, Vicente, Germani, Cristiano, and Palma, Gonzalo A., E-mail: achucar@lorentz.leidenuniv.nl, E-mail: vicente.atal@icc.ub.edu, E-mail: germani@icc.ub.edu, E-mail: gpalmaquilod@ing.uchile.cl. Wed . "Cumulative effects in inflation with ultra-light entropy modes". United States. doi:10.1088/1475-7516/2017/02/013.
@article{osti_22680042,
title = {Cumulative effects in inflation with ultra-light entropy modes},
author = {Achúcarro, Ana and Atal, Vicente and Germani, Cristiano and Palma, Gonzalo A., E-mail: achucar@lorentz.leidenuniv.nl, E-mail: vicente.atal@icc.ub.edu, E-mail: germani@icc.ub.edu, E-mail: gpalmaquilod@ing.uchile.cl},
abstractNote = {In multi-field inflation one or more non-adiabatic modes may become light, potentially inducing large levels of isocurvature perturbations in the cosmic microwave background. If in addition these light modes are coupled to the adiabatic mode, they influence its evolution on super horizon scales. Here we consider the case in which a non-adiabatic mode becomes approximately massless (''ultralight') while still coupled to the adiabatic mode, a typical situation that arises with pseudo-Nambu-Goldstone bosons or moduli. This ultralight mode freezes on super-horizon scales and acts as a constant source for the curvature perturbation, making it grow linearly in time and effectively suppressing the isocurvature component. We identify a Stückelberg-like emergent shift symmetry that underlies this behavior. As inflation lasts for many e -folds, the integrated effect of this source enhances the power spectrum of the adiabatic mode, while keeping the non-adiabatic spectrum approximately untouched. In this case, towards the end of inflation all the fluctuations, adiabatic and non-adiabatic, are dominated by a single degree of freedom.},
doi = {10.1088/1475-7516/2017/02/013},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 02,
volume = 2017,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
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