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SUMMARY:Galilean Genesis: An Alternative to inflation - Paolo Creminelli (
 ICTP)
DTSTART:20110321T130000Z
DTEND:20110321T140000Z
UID:TALK29137@talks.cam.ac.uk
CONTACT:Tasos Avgoustidis
DESCRIPTION:We propose a novel cosmological scenario\, in which standard i
 nflation is replaced by an expanding phase with a drastic violation of the
  Null Energy Condition (NEC): \\dot H >> H^2. The model is based on the re
 cently introduced Galileon theories\, that allow NEC violating solutions w
 ithout instabilities. The unperturbed solution describes a Universe that i
 s asymptotically Minkowski in the past\, expands with increasing energy de
 nsity until it exits the regime of validity of the effective field theory 
 and reheats. This solution is a dynamical attractor and the Universe is dr
 iven to it\, even if it is initially contracting. The study of perturbatio
 ns of the Galileon field reveals some subtleties\, related to the gross vi
 olation of the NEC and it shows that adiabatic perturbations are cosmologi
 cally irrelevant. The model\, however\, suggests a new way to produce a sc
 ale invariant spectrum of isocurvature perturbations\, which can later be 
 converted to adiabatic: the Galileon is forced by symmetry to couple to th
 e other fields as a dilaton\; the effective metric it yields on the NEC vi
 olating solution is that of de Sitter space\, so that all light scalars wi
 ll automatically acquire a nearly scale-invariant spectrum of perturbation
 s.
LOCATION:CMS\, Pav.B\, CTC Common Room (B1.19)
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