  Recently, we introduced the notion of "tracker fields," a form of
quintessence which has an attractor-like solution. Using this concept, we
showed how to construct models in which the ratio of quintessence to matter
densities today is independent of initial conditions. Here we apply the same
idea to the standard cold dark matter component in cases where it is composed
of oscillating fields. Combining these ideas, we can construct a model in which
quintessence, cold dark matter, and ordinary matter all contribute comparable
amounts to the total energy density today irrespective of initial conditions.
