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Title: Coupling structure of multi-field primordial perturbations

We investigate the coupling relations among perturbations in general multi-field models. We derived the equations of motion for both background and perturbations in a general basis. Within this formalism, we revisit the construction of kinematic orthogonal normal vectors using the successive time derivatives of the background field velocity. We show that the coupling relations among modes in this kinematic basis can be reduced, by employing the background equations of motion for the scalar fields and their high order time derivatives. There are two typical features in the field space: inflationary trajectory and geometry of the potential. Correspondingly, the couplings among modes fall into two categories: one is controlled only by the kinematic quantities, the other involves high order derivatives of the potential. Remarkably, the couplings of the first category, i.e. controlled by the kinematic quantities only, show a ''chain'' structure. That is, each mode is only coupled to its two neighbour modes.
Authors:
 [1]
  1. Astroparticule and Cosmologie, UMR 7164-CNRS, Université Denis Diderot-Paris 7, 10 rue Alice Domon et Léonie Duquet, 75205 Paris (France)
Publication Date:
OSTI Identifier:
22282620
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COUPLING; EQUATIONS OF MOTION; GEOMETRY; PERTURBATION THEORY; POTENTIALS; SCALAR FIELDS; SPACE; VECTORS; VELOCITY