Toward the correlated analysis of perturbative QCD observables

Abstract

We establish direct connection between ghost-free formulations of RG-invariant perturbation theory in the both Euclidean and Minkowskian regions. By combining the trick of resummation of the $\pi^2$-terms for the invariant QCD coupling and observables in the time-like region with fresh results on the "analyticized" coupling $\alpha_{\rm an}(Q^2)$ and observables in the space-like domain we formulate a self-consistent scheme, free of ghost troubles. The basic point of this joint construction is the "dipole spectral relation" emerging from axioms of local QFT. Then we consider the issue of the heavy quark thresholds and devise a global scheme for the data analysis in the whole accessible space-like and time-like domain with various numbers of active quarks. Observables in both the regions are presented in a form of non-power perturbation series with improved convergence properties. Preliminary estimates indicate that this global scheme produces results a bit different - on a few per cent level for $\bar{\alpha}_s$ - from the usual one, thus influencing the total picture of the QCD parameters correlation.