We consider the theory obtained by adding to the usual string frame dilaton gravity action specially constructed higher derivative terms motivated by the limited curvature construction of  and determine the spatially homogeneous and isotropic solutions to the resulting equations of motion. All solutions of the resulting theory of gravity with these symmetries are nonsingular and all curvature invariants are bounded. For initial conditions inspired by the pre-big-bang scenario solutions exist which correspond to a spatially flat Universe starting in a dilaton-dominated super inflationary phase with H > 0 and having a smooth transition to an expanding Friedmann Universe with H < 0. Hence, the graceful exit problem of pre-big-bang cosmology is solved in a natural way.
- Cosmological Phase Transitions
- Physics of the Early Universe
- Superstrings and Heterotic Strings
ASJC Scopus subject areas
- Nuclear and High Energy Physics