Curvature vacuum correlations in four-derivative gravity

Under the flat Minkowski space–time background, in the harmonic coordinate system, we calculate the expressions of the leading terms of several two-point curvature vacuum correlation functions in n dimensional four-derivative gravity, resulting in that the two-point curvature vacuum correlation functions are not zero, and discuss the relations between the four-derivative gravity and the R-gravity for the graviton propagator and the curvature correlation functions.