Nonperturbative corrections to the Kahler potential and the problem of dilaton stabilization

Friedmann-Robertson-Walker gravidilaton cosmological models with a dilaton potential generated by gaugino condensation and by nonperturbative corrections to the Kahler potential are analyzed within the framework of effective string gravitation. The question of dilaton stabilization by such potentials is investigated. It is shown that the existence of a range of dilaton values with a negative definite potential results in the possible existence of mixed expansion-contraction models with aflat space. The corresponding phase portraits are constructed for qualitatively different cases, illustrating the possibility of dilaton stabilization. Translated from Astrofizika, Vol. 42, No. 3, pp. 465–476, July–September, 1999.