Physical renormalization schemes and asymptotic safety in quantum gravity

Understand

The methods of the renormalization group and the $\varepsilon$-expansion are applied to quantum gravity revealing the existence of an asymptotically safe fixed point in spacetime dimensions higher than two.

• To facilitate this, physical renormalization schemes are exploited where the renormalization group flow equations take a form which is independent of the parameterisation of the physical degrees of freedom (i.e.
• the gauge fixing condition and the choice of field variables).
• Instead the flow equation depends on the anomalous dimensions of reference observables.