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SUMMARY:Influence of heavy modes on perturbations in multiple field inflat
 ion  - Xian Gao (APC Paris)
DTSTART:20121008T120000Z
DTEND:20121008T130000Z
UID:TALK39635@talks.cam.ac.uk
CONTACT:Camille Bonvin
DESCRIPTION:We investigate linear cosmological perturbations in multiple f
 ield inflationary models where some of the directions are light while othe
 rs are heavy (with respect to the Hubble parameter). By integrating out th
 e massive degrees of freedom\, we determine the multi-dimensional effectiv
 e theory for the light degrees of freedom and give explicitly the propagat
 ion matrix that replaces the effective sound speed of the one-dimensional 
 case. We then examine in detail the consequences of a sudden turn along th
 e inflationary trajectory\, in particular the possible breakdown of the lo
 w energy effective theory in case the heavy modes are excited. Resorting t
 o a new basis in field space\, instead of the usual adiabatic/entropic bas
 is\, we study the evolution of the perturbations during the turn. In parti
 cular\, we compute the power spectrum and compare with the result obtained
  from the low energy effective theory.
LOCATION:CMS\, Pav.B\, CTC Common Room (B1.19)
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