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Hadronic Vacuum Polarization: (g-2)_{μ} versus Global Electroweak Fits.
Andreas Crivellin1,2, Martin Hoferichter3, Claudio Andrea Manzari1,2
1Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
Physical Review Letters
|September 11, 2020
Summary
The standard model
Area of Science:
- Particle Physics
- Quantum Field Theory
Background:
- Hadronic vacuum polarization (HVP) is essential for predicting the muon's anomalous magnetic moment (g-2)μ and electroweak precision observables.
- HVP contributes to the running of the fine-structure constant (Δαhad(5)), impacting global fits.
Purpose of the Study:
- To determine Δαhad(5) using modern electroweak precision data, including Higgs mass measurements.
- To compare this determination with values from e+e-→hadrons cross-section data and assess its implications for the muon g-2 anomaly.
Main Methods:
- Global analysis of electroweak precision data.
- Inclusion of the Higgs boson mass measurement in the fit.
- Comparison with experimental data from electron-positron annihilation into hadrons.
Main Results:
- A competitive, independent determination of Δαhad(5)|EW = 270.2(3.0)×10⁻⁴ was obtained from the global fit.
- This value is lower than the range derived from e+e-→hadrons data.
- The discrepancy suggests a potential tension between electroweak data and the muon g-2 anomaly if explained by HVP modifications.
Conclusions:
- The electroweak fit provides a precise, independent value for Δαhad(5).
- Reconciling the muon g-2 anomaly via HVP adjustments may shift the focus of new physics searches from the muon g-2 to electroweak precision observables.
- This tension could indicate new physics beyond the Standard Model.
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