Renormalization group flow in CDT

We perform a first investigation of the coupling constant flow of the nonperturba-tive lattice model of four-dimensional quantum gravity given in terms of Causal Dynamical Triangulations (CDT). After explaining how standard concepts of lat-tice field theory can be adapted to the case of this background-independent theory, we define a notion of “lines of constant physics ” in coupling constant space in terms of certain semiclassical properties of the dynamically generated quantum universe. Determining flow lines with the help of Monte Carlo simulations, we find that the second-order phase transition line present in this theory can be in-terpreted as a UV phase transition line if we allow for an anisotropic scaling of space and time. 1 ar X iv