DBI Realizations of the Pseudo-Conformal Universe and Galilean Genesis
  Scenarios
  The pseudo-conformal universe is an alternative to inflation in which the
early universe is described by a conformal field theory on approximately flat
space-time. The fields develop time-dependent expectation values, spontaneously
breaking the conformal symmetries to a de Sitter subalgebra, and fields of
conformal weight zero acquire a scale invariant spectrum of perturbations. In
this paper, we show that the pseudo-conformal scenario can be naturally
realized within theories that would ordinarily be of interest for DBI
inflation, such as the world-volume theory of a probe brane in an AdS bulk
space-time. In this approach, the weight zero spectator field can be associated
with a geometric flat direction in the bulk, and its scale invariance is
protected by a shift symmetry.
