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δ M formalism: a new approach to cosmological perturbation theory in anisotropic inflation

Talebian Ashkezari, A ; Sharif University of Technology | 2018

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  1. Type of Document: Article
  2. DOI: 10.1088/1475-7516/2018/03/001
  3. Publisher: Institute of Physics Publishing , 2018
  4. Abstract:
  5. We study the evolution of the metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized "Separate Universe" approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the δ M formalism for calculating the evolution of the linear tensor perturbations in anisotropic inflation models in almost the same way that the so-called δ N formula is applied to the super-horizon dynamics of the curvature perturbations. Similar to her twin formula, δ N, this new method can substantially reduce the amount of calculations related to the evolution of tensor modes. However, it is not as general as δ N; it is a "perturbative» formula and solves the shear only to linear order. In other words, it is restricted to weak shear limit. © 2018 IOP Publishing Ltd and Sissa Medialab
  6. Keywords:
  7. Cosmological perturbation theory ; Ination
  8. Source: Journal of Cosmology and Astroparticle Physics ; Volume 2018, Issue 3 , 2018 ; 14757516 (ISSN)
  9. URL: https://iopscience.iop.org/article/10.1088/1475-7516/2018/03/001