Short Distance Freedom of Quantum Gravity
  Fourth order derivative gravity in 3+1-dimensions is perturbatively renormalizable and is shown to describe a unitary theory of gravitons in a limited coupling parameter space. The running gravitational constant which includes graviton contribution is computed. Generically, gravitational Newton's constant vanishes at short distances in this perturbatively renormalizable and unitary theory. 
Gaurav Narain and Ramesh Anishetty
hep-th gr-qc hep-ph