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SUMMARY:\\lambda \\phi^4 in de Sitter

 space
DTSTART:20190108T140000
DTSTAMP:20260428T033803Z
UID:e226257960e0cd90d5a6efaf319f52af48cb0a735f7aa4cb1607134d
CATEGORIES:Conferences - Seminars
DESCRIPTION:Leonardo Senatore (Stanford U.)\nCorrelation functions in mass
 less \\lambda \\phi^4 in de Sitter space are IR divergent\, indicating tha
 t the interacting vacuum of the theory is non-perturbatively far from the 
 free vacuum. This gives rise to worries that de Sitter space might actuall
 y be unstable. We introduce two different perturbative schemes for sub-hor
 izon and super-horizon modes. While short modes are solved for with the fa
 miliar expansion in powers of the coupling constant \\lambda\, for the lon
 g modes we develop a non-perturbative formalism\, that allows us to find a
  non-perturbative solution and to expand around it in powers of \\hbar\, g
 radients and square-root of \\lambda. At leading order in all these parame
 ters\, the density matrix for the long modes satisfies a Fokker-Planck equ
 ation\, as envisioned long-time ago by Starobinsky. A generalized equation
  allows us to obtain the corrections in all the expansion parameters. We c
 ompute explicitly the ones in square-root of \\lambda\, which are the lead
 ing ones. We provide several checks\, such as the fact that\, on the stati
 c patch\, correlation functions are thermal. Our results provide not only 
 a solution to the problem of \\lambda \\phi^4 in de Sitter space\, but als
 o offer a rigorous proof of the existence of slow-roll eternal inflation.
LOCATION:BSP 727 https://plan.epfl.ch/?room==BSP%20727
STATUS:CONFIRMED
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