PRIMORDIAL PERTURBATIONS FROM INFLATION

The generation of initial perturbations from cosmic inflation is considered. Several different mechanisms of non-standard origin - i.e., nonflat or nongaussian inhomogeneities - are reviewed. Nonstandard isocurvature and adiabatic perturbations, as well as nonperturbative inhomogeneities can be produced along with the standard adiabatic perturbations during inflations. The departure of standard perturbations crucially depends on inflationary scenario. The nongaussianity of fluctuations in the context of cosmology is discussed.