Status of Leading-Order Hadronic Vacuum Polarization Dispersion Calculation

Abstract

The leading-order hadronic contribution to the muon magnetic anomaly $a_{\mu }\equiv (g_{\mu }-2)/2$, calculated using a dispersion integral of $e^{+}{e}^{-}$ annihilation data and τ decay data, is briefly reviewed. This contribution has the largest uncertainty to the predicted value of $a_{\mu }$, which differs from the experimental value by ∼ 3.6 (2.4) standard deviations for the $e^{+}{e}^{-}$ (τ) based analysis. New results since the last workshop and main open issues on the subject are discussed.