QCD Effective Coupling in the Infrared Region

Understand

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.