The hadronic vacuum polarisation contributions to the muon $g-2$

Abstract

The hadronic vacuum polarisation contributions to the anomalous magnetic moment of the muon, $a_{\mu }^{\mathrm{had},\mathrm{VP}}$ have been re-evaluated from the combination of $e^{+}{e}^{-}\to \mathrm{hadrons}$ cross section data. Focus has been placed on the development of a new data combination method, which fully incorporates all correlated statistical and systematic uncertainties in a bias free approach. Using these combined data have resulted in estimates of the hadronic vacuum polarisation contributions to $g-2$ of the muon of $a_{\mu }^{\mathrm{had},\mathrm{LO}\mathrm{VP}}=(693.27\pm 2.46)\times 10^{-10}$ and $a_{\mu }^{\mathrm{had},\mathrm{NLO}\mathrm{VP}}=(-9.82\pm 0.04)\times 10^{-10}$. The new estimate for the Standard Model prediction is found to be $a_{\mu }^{\mathrm{SM}}=(11659182.05\pm 3.56)\times 10^{-10}$, which is $3.7\sigma$ below the current experimental measurement. In addition, the prediction for the hadronic contribution to the QED coupling at the $Z$ boson mass has been calculated to be $\Delta {\alpha }_{\mathrm{had}}^{(5)}(M_Z^2)=(276.11\pm 1.11)\times 10^{-4}$, resulting in ${\alpha }^{-1}(M_Z^2)=128.946\pm 0.015$.

Comments: Presented at Old and New Strong Interactions from LHC to Future Colliders (LFC17), C17-09-11.6