The strong coupling constant at large distances
Abstract
In this paper we discuss effective strong coupling constants. Those are well behaved in the low-Q2 domain, contrarily to alphas from pQCD. We present an extraction of an effective strong coupling constant from Jefferson Lab polarized data at intermediate and low Q2. We also show how these data, together with spin sum rules, allow us to obtain the effective coupling constant over the entire Q2 range. We then discuss the relation between the experimentally extracted coupling constant and theoretical calculations at low Q2. We conclude on the importance of such study for the application of the AdS/CFT correspondence to QCD.
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