Implications of a frame dependent gravitational effective action for
  perturbations on the Robertson-Walker Metric
  In earlier work we showed that a frame dependent effective action motivated
by the postulates of three-space general coordinate invariance and Weyl scaling
invariance exactly mimics a cosmological constant in Robertson-Walker (RW)
spacetimes. Here we study the implications of this effective action for small
fluctuations around a spatially flat RW background geometry. The equations for
the conserving extension of the modified stress-energy tensor can be integrated
in closed form, and involve only the metric perturbation $h_{00}$. Hence the
equations for tensor and vector perturbations are unmodified, but there are
Hubble scale additions to the scalar perturbation equations, which nonetheless
admit no propagating wave solutions. Consequently, there are no modifications
to standard gravitational wave propagation theory, but there may be observable
implications for cosmology. We give a self-contained discussion, including an
analysis of the restricted class of gauge transformations that act when a frame
dependent effective action is present.
