[OKC-CosmologyGravity] OKC Theory Seminar on Thursday, Dec 14 at 13.15 in Nordita 132:028

[Martina Gerbino]

Dear C&G group,

please save the date for the next Theory WG meeting. Tomorrow at 13:15 in Nordita 132:028?. See below.

Cheers,
Martina
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The next OKC Theory Working Group seminar is on:

Date:    Thursday Dec 14, at 13.15

Place:   Nordita 132:028

Speaker: Sadra Jazayeri (Institute for Theoretical Physics, Utrecht & IPM,
          Tehran)

Title:   Systematics of Adiabatic Modes in Cosmology

Abstract: Adiabatic modes (ADMs) play an essential role in derivation of
soft theorems in Cosmology. They also give us non-trivial solutions to the
Einstein perturbed equations that are almost independent from the matter
content of the universe. They are defined as the physical perturbations
(on the top of a fixed FRW universe), that can be locally removed by a
local coordinate transformation.  In this work we systematically construct
the adiabatic modes and find new time-dependent ones. In the light of a
new time dependent ADM for graviton, we show that alternative theories to
inflation enjoy asymptotic symmetries associated with soft gravitons. We
point out adiabaticity of vector perturbations and mention the relevance
of this finding to primordial magnetogenesis.  New ADMs, possess
interesting features. In particular, they can be either mixed or pure in
terms of scalar-vector-tensor decomposition. The long mode of the tensor
perturbation is able to have quantum behavior even on large scales.
Moreover, we figure out that some ADMs can not be monochromatic but
instead they will be continued into spherical waves.

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Best regards,
Fawad

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