Non-thermal production of dangerous relics in the early universe

Many models of supersymmetry breaking, in the context of either supergravit y or superstring theories, predict the presence of particles with weak scal e masses and Planck-suppressed couplings. Typical examples are the scalar m oduli and the gravitino. Excessive production of such particles in the earl y Universe destroys the successful predictions of nucleosynthesis. In parti cular, the thermal production of these relics after inflation leads to a bo und on the reheating temperature, T-RH less than or similar to 10(9) GeV. I n this paper we show that the non-thermal generation of these dangerous rel ics may be much more efficient than the thermal production after inflation. Scalar moduli fields may be copiously created by the classical gravitation al effects on the vacuum state. Consequently, the new upper bound on the re heating temperature is shown to be, in some cases, as low as 100 GeV. We al so study the non-thermal production of gravitinos in the early Universe, wh ich can be extremely efficient and overcome the thermal production by sever al orders of magnitude, in realistic supersymmetric inflationary models.