Local scale-dependent non-gaussian curvature perturbations at cubic order

Abstract

We calculate non-Gaussianities in the bispectrum and trispectrum arising from the cubic termin the local expansion of the scalar curvature perturbation. We compute to three-loop orderand for general momenta.A procedure for evaluating the leading behavior of the resulting loop-integrals is developed and discussed.Finally, we survey unique non-linear signals which could arise from the cubic term in the squeezed limit.In particular, it is shown that loop corrections can cause fNLsq. to change sign as the momentumscale is varied. There also exists a momentum limit where τNL < 0 can be realized.