AIMS Seminar - Non-gaussianities in Multifield Inflation: The approach to adiabaticity and the Fate of fnl

Location: 
AIMS Research Centre
Date: 
Mon, 21/11/2011 - 12:00 - 13:00
Speaker: 
Navin Sivanandam (African Institute for Mathematical Sciences)

Abstract:
While the leading non-gaussian contribution to the inflationary perturbations (the bispectrum) is slow-roll suppressed in canonical single field models of inflation, there exist several two-field scenarios where a large fnl can apparently be generated. Moreover, the local form of the bispectrum appears to be unique to multi-field inflationary models. However, models of inflation with more than one field are inherently incomplete unless we carefully track the fluctuations in the cosmological fluid until such time as those fluctuations become adiabatic. Careful investigations of one particular method of approach to adiabaticity revealed that the apparent non-gaussianities are transient, suggesting in turn that a large fnl of the local form may be out of reach in some classes of multi-field models.