QCD Effective Coupling in the Infrared Region

Abstract

We estimate the QCD effective charge ${\alpha }_s$ in the low-energy region by exploiting the conventional meson spectrum within a relativistic quantum-field model based on analytic confinement. The ladder Bethe-Salpeter equation is solved for the masses of two-quark bound states. We found a new, independent and specific infrared-finite behavior of QCD coupling below energy scale 1 GeV. Particularly, an infrared-fixed point is extracted at ${\alpha }_s(0)\simeq 0.757$ for confinement scale $\Lambda =345$ MeV. As an application, we estimate masses of some intermediate and heavy mesons and obtain results in reasonable agreement with recent experimental data.

Comments: 16 pages, 5 figures, 2 tables