The Effective Theory of Gravity and Dynamical Vacuum Energy
  Gravity and general relativity are considered as an Effective Field Theory
(EFT) at low energies and macroscopic distance scales. The effective action of
the conformal trace anomaly of light or massless quantum fields has significant
effects on macroscopic scales, owing to its describing light cone singularities
not captured by an expansion in local curvature invariants. A compact local
form for the Wess-Zumino effective action of the conformal anomaly and stress
tensor is given, involving the introduction of a new light scalar, which it is
argued should be included in the low energy effective action for gravity. This
scalar conformalon couples to the conformal part of the spacetime metric and
allows the effective value of the vacuum energy, described as a condensate of a
4-form abelian gauge field, to change in space and time. The EFT of vacuum
energy thereby replaces the fixed constant Lambda of the classical theory with
a dynamical condensate whose natural ground state value in empty flat space is
Lambda_eff = 0 identically. In addition to the conformal anomaly, the principal
physical inputs to the EFT are a topological vacuum susceptibility
characterizing the coupling of the 4-form condensate to the anomaly current, in
analogy to the chiral susceptibility of QCD, and the extension of the fermion
anomaly to a general Einstein-Cartan space including torsion. By allowing
Lambda_eff to vary rapidly near a black hole horizon, the EFT of dynamical
vacuum energy provides an effective Lagrangian framework for gravitational
condenstate stars, as the final state of complete gravitational collapse
consistent with quantum theory. The possible consequences of dynamical vacuum
dark energy in cosmology, the cosmic coincidence problem, and the role of
conformal invariance for other fine tuning issues in the Standard Model are
discussed.
