GENERAL COSMOLOGICAL FEATURES OF THE EINSTEIN-YANG-MILLS-DILATON SYSTEM IN STRING THEORIES

We establish the main features of homogeneous and isotropic dilaton, metric and Yang-Mills field configurations in a cosmological framework. We discuss the way inflationary solutions can be obtained for a quadratic dilaton potential. Special attention is paid to the energy exchange between the dilaton and the Yang-Mills field and, in particular, a new energy exchange term is identified which may lead to a possible solution of the Polonyi problem in 4-dimensional string models and in dynamical supersymmetry breaking scenarios.