In the framework of the Bethe-Salpeter formalism used in previous papers to
evaluate the quarkonium spectrum, here we reverse the point of view to extract
an ``experimental'' running coupling alpha_s(Q^2) in the infrared (IR) region
from the data. The values so obtained agree within the errors with the
Shirkov-Solovtsov analytic coupling for 200 MeV <Q< 1.2 GeV, thus giving a very
satisfactory unifying description of high and low energy phenomena. Below 1 GeV
however alpha_s(Q^2) seems to vanish as Q to 0. The paper is based on a work in
progress in collaboration with D.V.Shirkov.Comment: Talk given at 7th International Conference on Quark Confinement and
the Hadron Spectrum, Azores - Portugal, 2-7 Sep 2006. To be published in AIP
Conf.Pro
