Large regular QCD coupling at Low Energy?

TL;DR

This paper reviews recent progress in applying ghost-free Analytic Perturbative Theory to low-energy QCD, suggesting it can reliably describe hadronic phenomena down to a few hundred MeV.

Contribution

It demonstrates the potential of ghost-free analytic QCD models to provide a consistent and parameter-free description of low-energy hadronic physics.

Findings

Successful application to meson spectra analysis

Agreement with spin-dependent sum rules below 1 GeV

Supports combined perturbative and non-perturbative approach

Abstract

The issue is the expediency of the QCD notions use in the low energy region down to the confinement scale, and, in particular, the efficacy of the QCD invariant coupling \bar{\alpha}_s(Q^2) with a minimal analytic modification in this domain. To this goal, we overview a quite recent progress in application of the ghost-free Analytic Perturbative Theory approach (with no adjustable parameters) for QCD in the region below 1 GeV. Among them the Bethe--Salpeter analysis of the meson spectra and spin-dependent (polarization) Bjorken sum rule. The impression is that there is a chance for the theoretically consistent and numerically correlated description of hadronic events from Z_0 till a few hundred MeV scale by combination of analytic pQCD and some explicit non-perturbative contribution in the spirit of duality. This is an invitation to the practitioner community for a more courageous use of ghost-free QCD coupling models for data analysis in the low energy region.