Ghosts and Stability of Asymptotical Safe Gravity in the Minkowski Background

We investigate the problems of ghosts and stability in the framework of asymptotical safe theory of gravity in the Minkowski background. Within one loop corrections, we obtain explicitly the constraints on the coupling parameters. Applying them to the coupling constant recently-obtained at the fixed point, we find that the corresponding theory is both ghost-free and stable. Our results can be easily generalized to high order corrections.