What is the Principle of Maximum Conformality?

Question

I'm trying to understand this article about an advance in the theoretical understanding of QCD which centers on the Principal of Maximum Conformality. What is this Principle? In other words, what is being maximized and what does this tell us about the structure of QCD? Also, is this a new principle or a new application of an old principal?

Here's the full paper on the principle's application to top physics.

Answer 1

It is an approach to perturbative QCD which resolves ambiguities regarding the renormalization scale of the theory. It is done by summing terms for which the $\beta$-function is non-zero into the running coupling. In this sense, the remaining terms are now "maximally conformal" due to $\beta=0$. This results in predictions independent of the renormalization scheme. This approach seems to be relatively new, see http://arxiv.org/abs/1107.0338 for a detailed treatment.