A Modal Approach to the Numerical Calculation of Primordial
  non-Gaussianities
  We propose a new method to numerically calculate higher-order correlation
functions of primordial fluctuations generated from any early-universe
scenario. Our key-starting point is the realization that the tree-level In-In
formalism is intrinsically separable. This enables us to use modal techniques
to efficiently calculate and represent non-Gaussian shapes in a separable form
well suited to data analysis. We prove the feasibility and the accuracy of our
method by applying it to simple single-field inflationary models in which
analytical results are available, and we perform non-trivial consistency checks
like the verification of the single field consistency relation. We also point
out that the i epsilon prescription is automatically taken into account in our
method, preventing the need for ad-hoc tricks to implement it numerically.
