The strong coupling constant at large distances

TL;DR

This paper explores effective strong coupling constants at low and intermediate Q^2, using experimental data and sum rules, to bridge the gap between perturbative QCD and non-perturbative regimes, with implications for AdS/CFT correspondence.

Contribution

It provides a novel extraction of the effective strong coupling constant across all Q^2 ranges using Jefferson Lab data and spin sum rules, linking experimental results with theoretical models.

Findings

Effective coupling constant remains well-behaved at low Q^2.

Experimental data can be used to determine the coupling across the entire Q^2 spectrum.

Highlights the relevance of these findings for applying AdS/CFT to QCD.

Abstract

In this paper we discuss effective strong coupling constants. Those are well behaved in the low-Q^2 domain, contrarily to alpha_s from pQCD. We present an extraction of an effective strong coupling constant from Jefferson Lab polarized data at intermediate and low Q^2. We also show how these data, together with spin sum rules, allow us to obtain the effective coupling constant over the entire Q^2 range. We then discuss the relation between the experimentally extracted coupling constant and theoretical calculations at low Q^2. We conclude on the importance of such study for the application of the AdS/CFT correspondence to QCD.