Abstract:

Running couplings were introduced in quantum field theory to preserve perturbativity in scattering amplitudes, despite the appearance of large logs of external momenta. It is commonly believed that such logarithms are directly related to UV divergencies in one-loop perturbation theory. However, this is not completely true in higher derivative theories: on the one hand, large logs can also emerge from UV finite loop integrals due to IR effects; on the other hand, some UV divergent diagrams do not depend on external momenta. We define a new set of beta functions for quadratic gravity based on the explicit computation of large logs of momenta and discuss their features concerning the asymptotic UV behaviour of the theory and their gauge dependence.