Quantum Gravity Solution To The Cosmological Constant Problem
  A nonlocal quantum gravity theory is presented which is finite and unitary to all orders of perturbation theory. Vertex form factors in Feynman diagrams involving gravitons suppress graviton and matter vacuum fluctuation loops by introducing a low-energy gravitational scale, \Lambda_{Gvac} < 2.4\times 10^{-3} eV. Gravitons coupled to non-vacuum matter loops and matter tree graphs are controlled by a vertex form factor with the energy scale, \Lambda_{GM} < 1-10 TeV. 
J. W. Moffat