INFLATION IN S-DUAL SUPERSTRING MODELS

We study inflationary potentials in the framework of superstring theor ies, Successful inflation may occur due to chiral fields, but only aft er the dilaton and moduli are stabilized. This is achieved by demandin g an S-duality invariant potential. Then, it is possible to have infla tion at any scale and even to have more than one stage of inflation. T his occurs for a limited class of scalar potentials, where certain con ditions are obeyed, Density fluctuations of 10(-5) require the inflati onary potential to be at a scale of V-1/4 similar or equal to 5 X 10(1 5) GeV.