  The shortcomings of the Standard Big Bang Cosmological Model as well as their
resolution in the context of inflationary cosmology are discussed. The
inflationary scenario and the subsequent oscillation and decay of the inflaton
field are then studied in some detail. The density perturbations produced
during inflation and their evolution during the matter dominated era are
presented. The temperature fluctuations of the cosmic background radiation are
summarized. The non-supersymmetric as well as the supersymmetric hybrid
inflationary model is introduced and the `reheating' of the universe is
analyzed in the context of the latter and a left-right symmetric gauge group.
The scenario of baryogenesis via a primordial leptogenesis is considered in
some detail. It is, finally, pointed out that, in the context of a
supersymmetric model based on a left-right symmetric gauge group, hybrid
inflation, baryogenesis via primordial leptogenesis and neutrino oscillations
are linked. This scheme, supplemented by a familiar ansatz for the neutrino
Dirac masses and mixing of the two heaviest families and with the MSW
resolution of the solar neutrino puzzle, implies that the tau-neutrino mass
lies approximately between 1 and 9 eV. The mu-tau mixing angle is predicted to
lie in a narrow range which will be partially tested by the Chorus/Nomad
experiment.
