Alex Keshavarzi - Univ of Manchester - The muon g-2 in the SM and its connection with EW precision physics - via BLUEJEANS

US/Central
Description

The Muon g-2 Theory Initiative has, after a four-year international collaborative effort, released the first community approved value for the Standard Model (SM) calculation of the anomalous magnetic moment of the muon. The QED and EW contributions have been rigorously checked and are firmly established. Hadronic contributions are responsible for almost all of the theoretical uncertainty, with these contributions necessarily calculated using non-perturbative methods. The recent efforts from the Muon g-2 Theory Initiative have vastly improved the calculation of the hadronic contributions using either data-driven dispersive approaches, or lattice QCD. The final result for the SM prediction is smaller than the Brookhaven (BNL) experimental measurement by 3.7σ, substantiating the enduring hint for new physics. This discrepancy may possibly be confirmed by the upcoming measurements from the new Fermilab Muon g-2 experiment, and also by the future J-PARC experiment. Recently, studies have performed to investigate the possibility that the muon g-2 discrepancy could be explained by an underestimated value for the hadronic vacuum polarization (HVP) contributions. HVP effects enter several precisely measured electroweak (EW) observables and corresponding constraints are used to show that explaining the muon g-2 discrepancy by a larger HVP effect is largely ruled out by EW precision data (and effects on other observables). This is particularly important given a recent result from the lattice BMW collaboration, which finds a result for the HVP that is consistent with the BNL experimental measurement and a no-new-physics scenario.

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