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SEMINAIRE COMMUN CPT-CPPM.
ATTENTION: LIEU ET JOUR INHABITUELS
Primordial scalar (adiabatic) perturbations and tensor ones
(gravitational waves) are the main observable quantities which
remained from very early stages of evolution of our Universe.
Observational data show that the Fourier power spectrum of density
perturbations is very close to the flat (i.e., the
Harrison-Zeldovich) one and their statistics is Gaussian, in
agreement with predictions of the simplest versions of the
inflationary scenario of the early Universe. However, some small
deviations from the flat spectrum and the Gaussian statistics are
expected generically. I present recent theoretical results on the
primordial perturbation spectrum including the new general expression
for the spectrum of adiabatic perturbations unifying different ways
of their generation both during and after inflation, as well the two
exact solutions for inflaton field potentials producing a) the
exactly flat adiabatic spectrum, b) the constant ratio of
tensor/scalar perturbation power spectra. Also, the present
observational situation regarding local deviations from a smooth
approximately flat spectrum is reviewed.
