The Renormalization Scale-Setting Problem in QCD

Understand

A key problem in making precise perturbative QCD predictions is to set the proper renormalization scale of the running coupling.

• The conventional scale-setting procedure assigns an arbitrary range and an arbitrary systematic error to fixed-order pQCD predictions.
• In fact, this {\it ad hoc} procedure gives results which depend on the choice of the renormalization scheme, and it is in conflict with the standard scale-setting procedure used in QED.
• Predictions for physical results should be independent of the choice of scheme or other theoretical conventions.