On non-Gaussianities in single-field inflation

We study the impact of higher dimension operators in the inflaton Lagrangian on the non-gaussianity of the scalar spectrum. These terms can strongly enhance the effect without spoiling slow-roll, though it is difficult to exceed f_NL ~ 1. In particular we explicitly calculate the 3-point function given by an higher derivative interaction of the form (\∇\φ)^4, which is expected to give the most important contribution.