Low-energy gluon to the vacuum polarization of heavy quarks
We calculate a correction to the effective electromagnetic current at low energies, induced by a heavy-quark loop, and determine the analytic structure of the vacuum polarization function at small q2, for which an explicit expression is given to the O(αs3) order of perturbation theory. Implications to the high-precision analysis of experimental data on heavy-quark production in e+e− annihilation are discussed.