Review of recent leading-order hadronic vacuum polarization calculation

Abstract

The leading-order hadronic contribution to the muon magnetic moment anomaly $a_\mu\equiv (g_\mu-2)/2$, calculated using a dispersion integral of $e^+e^-$ annihilation data and $\tau$ data, is briefly reviewed. This contribution has the largest uncertainty to the predicted value of $a_\mu$, which differs from the direct measurement by $\sim 3.6 (2.4)$ standard deviations for the $e^+e^- (\tau)$ based analysis. Recent results and main open issues on the subject are discussed.