We examine the dynamical implications of an interaction between some of the fluid components of the universe. We consider the combination of three matter components, one of which is a perfect fluid and the other two are interacting. The interaction term generalizes the cases found in scalar field cosmologies with an exponential potential. We find that attracting scaling solutions are obtained in several regions of parameter space, that oscillating behavior is possible, and that new curvature scaling solutions exist. We also discuss the inflationary behavior of the solutions and present some of the constraints on the strength of the coupling, namely, those arising from nucleosynthesis.

• Received 7 November 2000

DOI:https://doi.org/10.1103/PhysRevD.63.083506