Stabilizing Dilaton and Moduli Vacua in String and M–Theory Cosmology

We show how non-trivial form fields can induce an effective potential for the dilaton and metric moduli in compactifications of type II string theory and M–theory. For particular configurations, the potential can have a stable minimum. In cosmological compactifications of type II theories, we demonstrate that, if the metric moduli become fixed, this mechanism can then lead to the stabilization of the dilaton vacuum. Furthermore, we show that for certain cosmological M–theory solutions, non-trivial forms lead to the stabilization of moduli. We present a number of examples, including cosmological solutions with two solitonic forms and examples corresponding to the infinite throat of certain p–branes. ∗Supported by Deutsche Forschungsgemeinschaft (DFG) and Nato Collaborative Research Grant CRG. 940784.