Unitary and Renormalizable Theory of Higher Derivative Gravity

In 3+1 space-time dimensions, fourth order derivative gravity is perturbatively renormalizable. Here it is shown that it describes a unitary theory of gravitons (with/without an additional scalar) in a limited coupling parameter space which includes standard cosmology. The running of gravitational constant which includes contribution of graviton is computed. It is shown that generically Newton's constant vanishes at short distance in this perturbatively renormalizable and unitary theory.