Cosmological models with dynamical Lambda in scalar-tensor theories - art.no. 123501

In the context of a family of scalar-tensor theories with a dynamical Lambd a that is a binomial on the scalar field, the cosmological equations are co nsidered. A general baryotropic state equation p = (gamma - 1)rho, for a pe rfect fluid is used for the matter content of the Universe. Some Friedmann- Robertson-Walker exact solutions are found; they have a scale factor which shows exponential or power law dependence on time. For some models the sing ularity can be avoided. Cosmological parameters such as Omega(m), Omega(Lam bda), q(0), and t(0) are obtained and compared with observational data [S05 56-2821(99)00220-9].