The strong coupling constant at low Q^2

Abstract

We extract an effective strong coupling constant using low-Q^2 data and sum rules. Its behavior is established over the full Q^2-range and is compared to calculations based on lattice QCD, Schwinger-Dyson equations and a quark model. Although the connection between all these quantities is not known yet, the results are surprisingly alike. Such a similitude may be related to quark-hadron duality.

6 pages, Contribution to the proceedings of the First Workshop on Quark-Hadron Duality and the Transition to pQCD (Duality05, Frascati, June 6-8 2005)