The Muon g-2 experiment at Fermilab has recently published the final measurement of the muon anomalous magnetic moment, reaching an unprecedented precision of 127 parts per billion (ppb), well below the original design goal of 140 ppb. This result serves as a critical reference point for theory, placing a benchmark to probe the Standard Model. The experiment is based on the precise...
The Muon g-2 Collaboration has recently measured the anomalous magnetic moment of the muon, $a_\mu$, with an unprecedented precision of about 0.13 ppm. To fully exploit this remarkable achievement, theoretical predictions must reach a comparable level of accuracy. A major challenge arises from the leading hadronic vacuum polarization (HVP) contribution, which needs to be determined with...
The hadronic vacuum polarization (HVP) contributions to the muon g−2 are the crucial quantities to resolve whether new physics is present or not in the comparison between the Standard Model (SM) prediction and experimental measurements at Fermilab. They are commonly and historically determined via dispersion relations using a vast catalogue of experimentally measured, low-energy e+e−→hadrons...
After a brief review of the data driven approach for the determination of the hadronic contribution to the vacuum polarization, the focus of the talk will be on the challenges posed by the measurement of the hadronic cross section and possible issues of theoretical origin. Also the spacelike approach, implemented through the MUonE experiment and its future perspectives will be discussed.
The final result on the measurement of the muon gyromagnetic anomaly, recently released by the E989 Collaboration at Fermilab, is a solid textbook reference for theory and experiment alike. It is not, however, the end of the story. The discrepancies in the theoretical approaches between lattice and data-driven calculations, compounded by the tensions in the current experimental determinations...
