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Title: Adiabatic and isocurvature perturbation projections in multi-field inflation

Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry, seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the isocurvature perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic perturbation in the flat field space limit.
Authors:
 [1] ;  [2]
  1. Department of Physics and Astronomy, University of Canterbury, Rutherford Building, Christchurch (New Zealand)
  2. School of Physics and Astronomy,University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)
Publication Date:
OSTI Identifier:
22282713
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 08; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; COSMOLOGY; EVOLUTION; INFLATIONARY UNIVERSE; INFLATONS; PERTURBATION THEORY; POTENTIALS; RELICT RADIATION; SPACE