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SUMMARY:From symmetries to cosmological observables
DTSTART:20180531T140000
DTEND:20180531T153000
DTSTAMP:20260510T201239Z
UID:0130d5cfb875f7b120e785b2b117f998c9836ccf8902c6f256e1f908
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Enrico Pajer (Utrecht University)\nMany models of inflatio
 n in field theory require an underlying approximate shift symmetry to driv
 e a prolonged phase of accelerated expansion. In UV-finite theories of gra
 vity such as string theory\, the shift symmetry is generically required fo
 r successful models. Despite the crucial role it plays\, the observable\, 
 model independent consequences of a shift symmetry are yet unknown. In thi
 s talk\, I will derive these consequences for primordial curvature correla
 tors in single clock inflation.\nI will discuss the two main paths from sy
 mmetry to cosmological observables: Effective Field Theories (EFT) and War
 d-Takahashi identities. First\, I will derive the restrictions on the well
 -known EFT of cosmological backgrounds (a.k.a. the EFT of Inflation) impli
 ed by a shift symmetry of the clock. The resulting EFT of shift-symmetric 
 cosmologies describes\, among other systems\, perfect and imperfect superf
 luids coupled to gravity and driven superfluids in the decoupling limit. S
 econd\, I will derive new Ward-Takahashi identities for the squeezed limit
  of cosmological correlators using the language of adiabatic modes. I will
  conclude discussing the yet unexplored class of generalized adiabatic mod
 es that arise from mixing spacetime diffeomorphism with internal symmetrie
 s.
LOCATION:BSP 727 https://plan.epfl.ch/?room==BSP%20727
STATUS:CONFIRMED
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