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arXiv · 1705.00263

Muon g-2 Theory: the Hadronic Part

Fred Jegerlehner
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Abstract

I present a status report of the hadronic vacuum polarization effects for the muon $g-2$, to be considered as an update of [1]. The update concerns recent new inclusive $R$ measurements from KEDR in the energy range 1.84 to 3.72 GeV. For the leading order contributions I find $a_μ^{\mathrm{had}(1)}=(688.07\pm 4.14)[688.77\pm3.38]\times 10^{-10}$ based on $e^+e^-$data [incl. $τ$ data], $a_μ^{\mathrm{had}(2)}= (-9.93\pm 0.07) \times 10^{-10}$ (NLO) and $a_μ^{\mathrm{had}(3)}= (1.22\pm 0.01) \times 10^{-10}$ (NNLO). Collecting recent progress in the hadronic light-by-light scattering I adopt $π^0,η,η'$ [$95 \pm 12$] + axial--vector [$8 \pm ~3$] + scalar [$-6\pm ~1$] + $π,K$ loops [$-20\pm 5$] + quark loops [$22\pm ~4$] + tensor [$1\pm ~0$] + NLO [$3\pm ~2$] which yields $ a^{(6)}_μ(\mathrm{lbl},\mathrm{had})=(103 \pm 29) \times 10^{-11}.$ With these updates I find $a_μ^{\rm exp}-a_μ^{\rm the}=(31.3\pm 7.7)\times 10^{-10}$ a 4.1 $σ$ deviation. Recent lattice QCD results and future prospects to improve hadronic contributions are discussed.

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Fred Jegerlehner. 2017-04-30. Muon g-2 Theory: the Hadronic Part. https://doi.org/10.1051/epjconf%2F201816600022

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