Superinflation and quintessence in the presence of an extra field
  We discuss the implication of the introduction of an extra field to the dynamics of a scalar field conformally coupled to gravitation in a homogeneous isotropic spatially flat universe. We show that for some reasonable parameter values the dynamical effects are similar to those of our previous model with a single scalar field. Nevertheless for other parameter values new dynamical effects are obtained. 
A. Figueiredo, T.M. Rocha Filho, E. Gunzig, L. Brenig, and A. Saa