Puzzles in the hadronic contributions to the muon anomalous magnetic moment

Abstract

We summarize recent developments in the Standard-Model evaluation of the anomalous magnetic moment of the muon $a_{\hat{I}}¼$, 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 $e^{+}{e}^{-}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}$ experiments in the contribution to $a_{\hat{I}}¼$ in the energy range up to 1 GeV, as well as in the corresponding contribution to the intermediate Euclidean window.

12 pages, 1 figure, proceedings for "21st Conference on Flavor Physics and CP Violation," "Les Rencontres de Physique de la Vallée d'Aoste," and "New Frontiers in Lepton Flavor"