Effective Field Theory of Multifield Inflation

Uploaded on


More in: Technology
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads


Total Views
On Slideshare
From Embeds
Number of Embeds



Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

    No notes for slide


  • 1. Effective Field Theory ofMulti-Field Inflation a la Weinberg Nima KhosraviAfrican Institute for Mathematical Sciences arXiv:1203.2266
  • 2. map: keywords: Effective Field Theory, Inflation
  • 3. Effective Field Theory an effective theory: is true for a certain domain of energy. two cases:  as a part of a true theory for whole energy scales  using EFT to simplify calculations!  in lack of a complete theory for the energy scales of interests  using EFT since there is no other choice!  constructing EFT, by considering e.g. symmetry properties of the model. 
  • 4. EFT for Multi-Field Inflation the most general form of Lagrangian up to the 4th order derivatives: after simplifications: before simplifications!
  • 5. perturbations: perturbations in single field model (Weinberg’s paper) -- it is up to 4th order of perturbations automatically. -- speed of sound ≠ 1 -- large non-Gaussianity ? -- speed of sound is constrained by validity of EFT!
  • 6. perturbations: multi-field case: background terms: perturbations!
  • 7. perturbations: two-field case: the most general form of the Lagrangian: second order perturbations!…. and cubic and quartic terms!. . . transition to adiabatic and entropy curvature perturbations! 
  • 8. perturbations: adiabatic & entropy modes adiabatic mode: entropy mode: Gordon et al. arXiv:astro-ph/0009131
  • 9. perturbations: adiabatic & entropy modes  as an example: second order perturbation terms (containing time derivatives) due to correction term: note that just these two combinations appear in this formalism!
  • 10. shape of non-Gaussianity due to previous slide: for example: equilateral NG local NGin adiabatic mode in entropy mode--- in this formalism the “Cosine” between different kinds of NG is fixed!
  • 11. amplitude of NG-- validity condition of EFT i.e. constrains theamplitude of NG!-- except if the curvature of classical (background) path be large!-- or: if by a mechanism (e.g. Vainshtein) one can modify the validitycondition of EFT!
  • 12. compare with Senatore & Zaldarriaga-- Senatore & Zaldarriaga model is based on Cheung et al.’s work!-- in Cheung’s work, EFT is constructed on perturbations’ level! -- since their model is single field, the perturbation isassociated to adiabatic mode!-- so in Senatore & Z., the entropy modes are added into a base withalready known adiabatic mode!but-- in our case we started with zeroth order term of perturbations. -- then defined the perturbations without any distinguishabilitybetween adiabatic and entropy modes!
  • 13. compare with Senatore & Zaldarriaga GR + a scalar field 1 perturbation Modification Modification (EFT) (EFT) 2 3Cheung et al. and Senatore & Z.: 0 perturbation 1 3Weinberg and this talk: 0 2 3
  • 14. compare with Senatore & Zaldarriaga so in Senatore & Zaldarriaga, the shift symmetry results in a Lagrangian similar toi.e. there are just derivatives of adiabatic and entropy perturbations! but in our model the case is different!
  • 15. compare with Senatore & Zaldarriaga shift symmetry: due toresults inwhich causes a new symmetry for adiabatic and entropy modes:
  • 16. conclusions-- this model does not predict a large non-Gaussianity except: -- for a highly curved classical path in phase-space! -- or if a shielding mechanism allows large first correctionterm in EFT.-- different shapes of non-Gaussianity are correlated!-- in contrast to Senatore & Zaldarriaga, we suggest EFT formulti-filed inflation should be constructed as
  • 17. thank you!