The Cosmological Moduli Problem, Supersymmetry Breaking and Stability in Postinflationary Cosmology

A survey of solutions to the cosmological moduli problem in string theory. The only extant proposal which may work is Intermediate Scale Inflation as proposed by Randall and Thomas. Supersymmetry preserving dynamics which could give large masses to the moduli is strongly constrained by cosmology and requires the existence of string vacuum states possessing properties different from those of any known vacuuum. Such a mechanism cannot give mass to the dilaton unless there are cancellations between different exponentially small contributions to the superpotential. Our investigation also shows that stationary points of the effective potential with negative vacuum energy do not correspond to stationary solutions of the equations of postinflationary cosmology. This suggests that supersymmetry breaking is a requirement for a successful inflationary cosmology.