Speaker: Marco Rocco
Abstract
The experimental measurement and the theoretical prediction of the muon magnetic moment anomaly, $a_\mu$, have reached an unprecedented level of precision. Yet, a significant discrepancy between the two persists. From the theoretical viewpoint, it is clear that the hadronic contribution to $a_\mu$ is the source of the disagreement. This is usually derived with so-called dispersive methods that employ experimental measures of $e^+e^- \to {\rm hadrons}$. On the other hand, alternative theoretical approaches such as QCD calculations on the lattice disagree with the dispersive approach, hinting instead at an agreement with the most recent experimental measurement at Fermilab.
In this talk, I will try to untangle this tortuous theoretical landscape with an overview of both approaches, highlighting the current status along with most recent developments and potential weak points. I will also discuss a third approach, represented by the MUonE experiment at CERN, that stems from an orthogonal version of the dispersive method.