QCD Effective Couplings in Minkowskian and Euclidean Domains

Abstract

We argue for essential upgrading of the defining equations (9.5) and (9.6) in Section 9.2 "The QCD coupling ... " of PDG review and their use for data analysis in the light of recent development of the QCD theory. Our claim is twofold. First, instead of universal expression (9.5) for QCD coupling $\barα_s$, one should use various ghost-free couplings $α_E(Q^2), α_M(s)...$ specific for a given physical representation, Euclidean, Mincowskian etc. Second, instead of power expansion (9.6) for observable, we recommend to use nonpower functional ones over particular functional sets ${{\cal A}_k(Q^2)}$, ${{\mathfrak A}_k(s)}...$ related by suitable integral transformations. We remind that use of this modified prescription results in a better correspondence of reanalyzed low energy data with the high energy ones.