Puzzles in the hadronic contributions to the muon anomalous magnetic moment
Gilberto Colangelo, Martin Hoferichter, Peter Stoffer · 2023
We summarize recent developments in the Standard-Model evaluation of the anomalous magnetic moment of the muon $a_\mu$, both in the hadronic-light-by-light and hadronic-vacuum-polarization contributions. The current situation for the latter is puzzling as we are confronted with multiple discrepancies that are not yet understood. We present updated fits of a dispersive representation of the pion vector form factor to the new CMD-3 data set and quantify the tensions with the other high-statistics $e^+e^-\to\pi^+\pi^-$ experiments in the contribution to $a_\mu$ in the energy range up to $1$ GeV, as well as in the corresponding contribution to the intermediate Euclidean window.