The quantum origin of cosmic structure: theory and observations
  The particle production process is reviewed, through which cosmic inflation
can produce a scale invariant superhorizon spectrum of perturbations of
suitable fields starting from their quantum fluctuations. Afterwards, in the
context of the inflationary paradigm, a number of mechanisms (e.g. curvaton,
inhomogeneous reheating etc.) through which such perturbations can source the
curvature perturbation in the Universe and explain the formation of structures
such as galaxies are briefly described. Finally, the possibility that cosmic
vector fields also contribute to the curvature perturbation (e.g. through the
vector curvaton mechanism) is considered and its distinct observational
signatures are discussed, such as correlated statistical anisotropy in the
spectrum and bispectrum of the curvature perturbation.
