Abstract
Hadronic vacuum polarization (HVP) is not only a critical part of the standard model (SM) prediction for the anomalous magnetic moment of the muon , but also a crucial ingredient for global fits to electroweak (EW) precision observables due to its contribution to the running of the fine-structure constant encoded in . We find that with modern EW precision data, including the measurement of the Higgs mass, the global fit alone provides a competitive, independent determination of . This value actually lies below the range derived from cross section data, and thus goes into the opposite direction as would be required if a change in HVP were to bring the SM prediction for into agreement with the Brookhaven measurement. Depending on the energy where the bulk of the changes in the cross section occurs, reconciling experiment and SM predictions for by adjusting HVP would thus not necessarily weaken the case for physics beyond the SM (BSM), but to some extent shift it from to the EW fit. We briefly explore some options of BSM scenarios that could conceivably explain the ensuing tension.
- Received 16 July 2020
- Accepted 3 August 2020
DOI:https://doi.org/10.1103/PhysRevLett.125.091801
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Published by the American Physical Society