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- Effective Field Theory of Multi-Field Inflation a la Weinberg

We

employ the effective field theory approach for multi-field inflation which is a

generalization of Weinberg's work. In this method the first correction terms in

addition to standard terms in the Lagrangian have been considered. These terms

contain up to the fourth derivative of the fields including the scalar field

and the metric. The results show the possible shapes of the interaction terms

resulting eventually in non-Gaussianity in a general formalism. In addition

generally the speed of sound is different but almost unity. Since in this

method the adiabatic mode is not discriminated initially so we define the

adiabatic as well as entropy modes for a specific two-field model. It has been

shown that the non-Gaussianity of the adiabatic mode and the entropy mode are

correlated in shape and amplitude. It is shown that even for speed close to

unity large non-Gaussianities are possible in multi-field case. The amount of

the non-Gaussianity depends on the curvature of the classical path in the

phase-space in the Hubble unit such that it is large for the large curvature.

In addition it is emphasized that the time derivative of adiabatic and entropy

perturbations do not transform due to the shift symmetry as well as the

original perturbations. Though two specific combinations of them are invariant

under such a symmetry and these combinations should be employed to construct an

effective field theory of multi-field inflation.

Collection/Series:

Event Type:

Seminar

Scientific Area(s):

Speaker(s):

Event Date:

Tuesday, July 30, 2013 - 11:00 to 12:30

Location:

Space Room

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