General formula for the running of local fNL

Abstract

We compute the scale dependence of fNL for models of multi-field inflation, allowing for an arbitrary field space metric. We show that, in addition to multi-field effects and self interactions, the curved field space metric provides another source of scale dependence, which arises from the field-space Riemann curvature tensor and its derivatives. The scale dependence may be detectable within the near future if the amplitude of fNL is not too far from the current observational bounds.

Comments: (v1) 9 pages, 1 figure; (v2) 10 pages, minor updates including the title, to appear in Physics Letters B