Robustness of the derivative expansion in Asymptotic Safety

Understand

We analyse the renormalisation group flow of quantum gravity at sixth order in the derivative expansion within the background field approximation.

• Non-linear field redefinitions are used to ensure that only essential couplings flow.
• Working within the universality class of General Relativity, with a vanishing cosmological constant, redundant couplings are fixed to their values at the Gaussian fixed point.
• This reduces the theory space to two dynamical essential couplings given by Newton's and the Goroff-Sagnotti coupling.