The dilaton classical solution and the supersymmetry breaking evolution in an expanding universe

The existence of a dilaton field in no scale supergravities implies that the only classical solutions of the dilaton + Einstein equations are those which predict at low temperatures a vast hierarchy between the supersymmetry breaking scale m sub(SUSY) (i.e. the typical squark, slepton and/or gaugino mass) and the Planck scale. At relatively low temperatures the dynamical quantities of the matter + dilaton system relax to some critical time trajectories with the property that the msub(SUSY)(t) and T(t) time trajectories stay proportional. The dimensionless ratio m sub(SUSY)/T is a fixed point of the theory and it is completely independent of the high temperature condition (T ≅ Msub(Planck)) of the matter + dilaton system. (orig.)