Cosmological 3-point correlators from holography
  We investigate the non-Gaussianity of primordial cosmological perturbations
using holographic methods. In particular, we derive holographic formulae that
relate all cosmological 3-point correlation functions, including both scalar
and tensor perturbations, to stress-energy correlation functions of a
holographically dual three-dimensional quantum field theory. These results
apply to general single scalar inflationary universes that at late times
approach either de Sitter spacetime or accelerating power-law cosmologies. We
further show that in Einstein gravity all 3-point functions involving tensors
can be obtained from correlators containing only positive helicity gravitons,
with the ratios of these to the correlators involving one negative helicity
graviton being given by universal functions of momenta, irrespectively of the
potential of the scalar field. As a by-product of this investigation, we obtain
holographic formulae for the full 3-point function of the stress-energy tensor
along general holographic RG flows. These results should have applications in a
wider holographic context.
