Inflation from superstrings

We investigate the possibility of obtaining inflationary solutions of the slow roll type from a low energy Lagrangian coming from superstrings. The advantage of such an approach is that in these theories the scalar potential has only one free parameter (the Planck scale) and therefore no unnatural fine tuning may be accommodated. We find that in any viable scheme the dilaton and the moduli fields have to be stabilized and that before this happens, no other field may be used as the inflaton. Then inflation may occur due to chiral matter fields. Demanding that the potential terms associated with the chiral fields do not spoil the dilaton and moduli minimization leads to severe constraints on the magnitude of the density fluctuations.