Atoms as Electron Accelerators for Measuring the Cross Section of e^{+}e^{-}→Hadrons

Area of Science:

• Particle Physics
• Quantum Electrodynamics
• Hadronic Physics

Background:

• The hadronic vacuum polarization (HVP) contribution to the anomalous magnetic dipole moment of the muon ((g-2)_μ) is crucial for testing the Standard Model.
• Current methods for determining the HVP contribution rely on electron-positron annihilation data, which have limitations.

Purpose of the Study:

• To propose and validate a novel method for measuring the hadronic cross section (σ_had(s)).
• To provide an alternative to existing techniques like initial-state radiation and energy scans for HVP calculations.

Main Methods:

• Utilizing positron annihilation off atomic electrons of a high Z target (e.g., Uranium-238).
• Leveraging relativistic electron velocities in inner atomic shells.
• Employing a high-intensity 12 GeV positron beam.

Main Results:

• The proposed method allows for the measurement of σ_had(s) with high statistical accuracy.
• This technique can cover the energy range from the two-pion threshold up to approximately sqrt(s) ~ 1 GeV.

Conclusions:

• The novel positron annihilation method offers a promising alternative for precise determination of the hadronic cross section.
• This approach can significantly improve the accuracy of HVP calculations for (g-2)_μ.