Speaker
Description
Predictions of processes in perturbative Quantum Chromodynamics (pQCD) critically depend on the appropriate choice of the renormalization scale $\mu_r$ to determine the correct running coupling in the perturbative expansion. In conventional scale setting, this scale is set to the characteristic process value, $Q$, and the uncertainty is estimated by varying $\mu_r$ within an arbitrary range $[Q/2, 2Q]$. However, this procedure introduces significant ambiguities in the choice of renormalization scheme and scale, limiting the precision of fixed-order predictions and directly impacting the results of numerous high-energy processes.
In this work, we present the Principle of Maximum Conformality (PMC) method as a robust solution to eliminate these ambiguities. The PMC absorbs the non-conformal terms into the effective coupling $\alpha_s(Q_{\text{PMC}})$ and establishes an optimal scale $Q_{\text{PMC}}$, resulting in a completely conformal perturbative series for the process. We apply the PMC method to improve the relation between pole and running heavy quark masses, the electroweak $\rho$ parameter, the determination of the decay width of the $W$ boson in hadrons, and other processes.
