Non-Gaussianity from Inflation
Wed, Jun. 06th 2007, 14:15
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
Non-linear effects, present in all inflation models, will cause the primordial perturbation spectrum to be non-Gaussian. While these effects are small, CMB data are getting sufficiently accurate that we might well expect to detect them in the near future with WMAP and PLANCK, providing us with new information about the early universe. In this talk I will discuss the formalism we developed to deal with the required non-linearity during inflation. Applying it to single-field inflation shows that there the non-Gaussianity is unobservably small.
However, next I will apply the formalism to general multiple-field inflation and derive an analytic expression for the bispectrum. From this we see that the influence of the isocurvature modes on the adiabatic mode at super-horizon scales can lead to a much larger non-Gaussianity. Specific examples are worked out.