Multi-Component Einstein-Cartan Cosmologies

Flat Friedmann universes filled by radiation, stiff fluid and a nonminimally coupled ghost scalar field with polynomial potentials of the fourth degree V(I broken vertical bar) are investigated in the framework of the Einstein-Cartan theory. Exact solutions are obtained and analyzed for an arbitrary coupling constant xi. It is shown that both singular and bouncing models with the late-time accelerated expansion are possible. A comparative analysis of the cosmological models with and without stiff fluid is carried out. The role of sources in the evolution of models is elucidated. Some conclusions from comparison of the presented results with other approaches in literature for accelerated expansion are made.