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HIGHLIGHTS OF 2021

High-precision lattice QCD calculations of the muon anomalous magnetic moment

In 2021, the most precise measurement of the muon’s anomalous magnetic moment and a new high-precision lattice quantum chromodynamics calculation have in turn kindled, then dimmed, hopes for seeing signs of new physics. State of the art calculations, made possible by a series of recent advances, will be key to understanding these conflicting results.

Key advances

  • In 2021, the most precise measurement of the muon’s anomalous magnetic moment was reported, showing a remarkable 4.2σ tension with the generally accepted theoretical value.

  • Reported at the same time, a new high-precision lattice quantum chromodynamics calculation is at odds with the theoretical value, reducing the tension with experiment to 1.6σ, yet increasing tensions with other theoretical calculations to 3.7σ.

  • The key to understanding these conflicting results lies in the value for the hadronic vacuum polarization. Advances in lattice quantum chromodynamics calculations will provide a new way to derive this quantity with high precision.

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Fig. 1: Theory–experiment and theory–theory tensions in the determination of the muon anomalous magnetic moment.

References

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Lehner, C. High-precision lattice QCD calculations of the muon anomalous magnetic moment. Nat Rev Phys 4, 14–15 (2022). https://doi.org/10.1038/s42254-021-00409-z

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  • DOI: https://doi.org/10.1038/s42254-021-00409-z

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