Quintessence dynamics with two scalar fields and mixed kinetic terms

Abstract

The dynamical properties of a model of dark energy in which two scalar fields are coupled by a noncanonical kinetic term are studied. We show that overall the addition of the coupling has only minor effects on the dynamics of the two-field system for both potentials studied, even preserving many of the features of the assisted quintessence scenario. The coupling of the kinetic terms enlarges the regions of stability of the critical points. When the potential is of an additive form, we find the kinetic coupling has an interesting effect on the dynamics of the fields as they approach the inflationary attractor, with the result that the combined equation of state of the scalar fields can approach $\ensuremath{-}1$ during the transition from a matter dominated universe to the recent period of acceleration.