Consistency relation and inflaton field redefinition in the delta N   formalism
  We compute for general single-field inflation the intrinsic non-Gaussianity due to the self-interactions of the inflaton field in the squeezed limit. We recover the consistency relation in the context of the delta N formalism, and argue that there is a particular field redefinition that makes the intrinsic non-Gaussianity vanishing, thus improving the estimate of the local non-Gaussianity using the delta N formalism. 
Guillem Domenech, Jinn-Ouk Gong and Misao Sasaki
astro-ph.CO gr-qc hep-ph hep-th