Effective Action from the Functional Renormalization Group

Abstract

We study the quantum gravitational system coupled to a charged scalar, Dirac fermions, and electromagnetic fields. We use the "exact" or "functional" renormalization group equation to derive the effective action ${\Gamma }_0$ by integrating the flow equation from the ultraviolet scale down to $k=0$. The resulting effective action consists of local terms and nonlocal terms with unique coefficients.

Comments: revised version, in agreement with journal version, citations added, 44 pages, 1 table