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 may 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