  The formulation of an exact functional renormalization group equation for
Quantum Einstein Gravity necessitates that the underlying effective average
action depends on two metrics, a dynamical metric giving the vacuum expectation
value of the quantum field, and a background metric supplying the coarse
graining scale. The central requirement of "background independence" is met by
leaving the background metric completely arbitrary. This bimetric structure
entails that the effective average action may contain three classes of
interactions: those built from the dynamical metric only, terms which are
purely background, and those involving a mixture of both metrics. This work
initiates the first study of the full-fledged gravitational RG flow, which
explicitly accounts for this bimetric structure, by considering an ansatz for
the effective average action which includes all three classes of interactions.
It is shown that the non-trivial gravitational RG fixed point central to the
Asymptotic Safety program persists upon disentangling the dynamical and
background terms. Moreover, upon including the mixed terms, a second
non-trivial fixed point emerges, which may control the theory's IR behavior.

High Energy Physics - Theory;General Relativity and Quantum Cosmology