The lowest order hadronic contribution to the $g-2$ factor of the muon is analyzed in the framework of the operator product expansion at short distances, and a QCD finite energy sum rule designed to quench the role of the $e^+ e^-$ data. This procedure reduces the discrepancy between experiment and theory, $\Delta a_\mu \equiv a^{ EXP}_\mu - a^{ SM}_\mu$, from $\Delta a_\mu = 28.7 (8.0) \times 10^{ -10}$ to $\Delta a_\mu = 19.2 (8.0) \times 10^{ -10}$, i.e. without changing the uncertainty.
Categories: hep-ph hep-lat