Dynamical vs spectator models of (pseudo-)conformal Universe
  We discuss two versions of the conformal scenario for generating scalar
cosmological perturbations: a spectator version with a scalar field conformally
coupled to gravity and carrying negligible energy density, and a dynamical
version with a scalar field minimally coupled to gravity and dominating the
cosmological evolution. By making use of the Newtonian gauge, we show that (i)
no UV strong coupling scale is generated below $M_{Pl}$ due to mixing with
metric perturbations in the dynamical scenario, and (ii) the dynamical and
spectator models yield identical results to the leading non-linear order. We
argue that these results, which include potentially observable effects like
statistical anisotropy and non-Gaussianity, are characteristic of the entire
class of conformal models. As an example, we reproduce, within the dynamical
scenario and working in comoving gauge, our earlier result on the statistical
anisotropy, which was originally obtained within the spectator approach.
