Speaker
Description
The anomalous magnetic moment of the muon, $a_\mu$, has long been a precision benchmark for testing the Standard Model, with persistent tensions between experiment and theoretical predictions driving intense activity over the past five years, particularly since 2020 with the publication of the first White Paper by the Muon $g-2$ Theory Initiative. This talk reviews the evolution of this puzzle in light of the latest White Paper, released earlier this year, which incorporates state-of-the-art first-principles determinations and effectively eliminates the discrepancy with experiment, confirming the Standard Model at the sub-ppm level. A key development has been the replacement of dispersive evaluations of the hadronic vacuum polarization with high-precision lattice QCD results, enabled by major methodological and computational advances. Nonetheless, residual tensions persist, most notably between lattice QCD and dispersive approaches, the latter still undergoing extensive reanalysis by multiple groups. I will summarize the current theoretical landscape, highlight the advances in lattice QCD that reshaped the comparison with experiment, and discuss the open issues and prospects for further scrutiny of $a_\mu$ as a probe of new physics.
