QCD Effective Coupling in the Infrared Region

TL;DR

This paper estimates the infrared behavior of the QCD effective charge using a relativistic quantum-field model and meson spectrum data, revealing a finite coupling at low energies around 0.757.

Contribution

It introduces a novel method to determine the infrared QCD coupling by solving the Bethe-Salpeter equation within an analytic confinement framework.

Findings

Infrared-fixed point at α_s(0) ≈ 0.757

Consistent meson mass predictions with experimental data

New insight into the low-energy behavior of QCD coupling

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.