Bound-State Approach to the QCD Coupling Constant at Low-Energy Scales

Abstract

We exploit theoretical results on the meson spectrum within the framework of a Bethe-Salpeter (BS) formalism adjusted for QCD, in order to extract an experimental coupling alpha(s)exp (Q2) below 1 GeV by comparison with the data. Our results for alpha(s)exp (Q2) exhibit a good agreement with the infrared safe analytic perturbation theory (APT) coupling from 1 GeV down to 200 MeV. As a main result, we claim that the combined BS-APT theoretical scheme provides us with a rather satisfactory correlated understanding of very high- and low-energy phenomena.