Under the assumption that cold dark matter and dark energy interact with each
other through a small coupling term, Q, we constrain the parameter space of
the equation of state w of those dark energy fields whose variation of the
field since last scattering do not exceed Planck's mass. We use three
parameterizations of w and two different expressions for Q. Our work
extends previous ones.Comment: 18 pages, 11 figures, accepted for publication on Physics Letters
