Spectral Running and Non-Gaussianity from Slow-Roll Inflation in Generalised Two--Field Models

Abstract

Theories beyond the standard model such as string theory motivate low energy effective field theories with several scalar fields which are not only coupled through a potential but also through their kinetic terms. For such theories we derive the general formulae for the running of the spectral indices for the adiabatic, isocurvature and correlation spectra in the case of two field inflation. We also compute the expected non-Gaussianity in such models for specific forms of the potentials. We find that the coupling has little impact on the level of non-Gaussianity during inflation.

26 pages, 10 figures, JHEP style, typos corrected, appendix and references added, published in JCAP