Recent improvements in the low energy e+e- annihilation data and their influence on the determination of the hadronic contribution to the running of the QED fine structure constant at m_Z are discussed. Using CMD-2 and KLOE measurements in the rho region we obtain Delta alpha(5)_had(s) = 0.02758 +/- 0.00035 at s = m_Z^2.
@article{arxiv.hep-ph/0506323,
title = {Low energy hadronic contribution to the QED vacuum polarization},
author = {H. Burkhardt and B. Pietrzyk},
journal= {arXiv preprint arXiv:hep-ph/0506323},
year = {2009}
}