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HIGHLIGHTS OF 2021

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

  • Year in Review
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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

  1. Abi, B. et al. Measurement of the positive muon anomalous magnetic moment to 0.46 ppm. Phys. Rev. Lett. 126, 141801 (2021).

    Article  ADS  Google Scholar 

  2. Borsanyi, S. et al. Leading hadronic contribution to the muon magnetic moment from lattice QCD. Nature 593, 51–55 (2021).

    Article  ADS  Google Scholar 

  3. Aoyama, T. et al. The anomalous magnetic moment of the muon in the Standard Model. Phys. Rep. 887, 1–166 (2020).

    Article  ADS  Google Scholar 

  4. Davier, M., Hoecker, A., Malaescu, B. & Zhang, Z. A new evaluation of the hadronic vacuum polarisation contributions to the muon anomalous magnetic moment and to \(\alpha ({m}_{Z}^{2})\). Eur. Phys. J. C 80, 241 (2020).

    Article  ADS  Google Scholar 

  5. Keshavarzi, A., Nomura, D. & Teubner, T. g − 2 of charged leptons, \(\alpha ({m}_{Z}^{2})\), and the hyperfine splitting of muonium. Phys. Rev. D 101, 014029 (2020).

    Article  ADS  Google Scholar 

  6. Blum, T. et al. Calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment. Phys. Rev. Lett. 121, 022003 (2018).

    Article  ADS  Google Scholar 

  7. Aubin, C. et al. Light quark vacuum polarization at the physical point and contribution to the muon g − 2. Phys. Rev. D 101, 014503 (2020).

    Article  ADS  Google Scholar 

  8. Lehner, C. & Meyer, A. S. Consistency of hadronic vacuum polarization between lattice QCD and the R ratio. Phys. Rev. D 101, 074515 (2020).

    Article  ADS  Google Scholar 

  9. Davies, C. T. H. et al. Hadronic-vacuum-polarization contribution to the muon’s anomalous magnetic moment from four-flavor lattice QCD. Phys. Rev. D 101, 034512 (2020).

    Article  ADS  Google Scholar 

  10. Gérardin, A. G. et al. Leading hadronic contribution to (g − 2)μ from lattice QCD with Nf = 2 + 1 flavors of O(a) improved Wilson quarks. Phys. Rev. D 100, 014510 (2019).

    Article  ADS  MathSciNet  Google Scholar 

  11. Blum, T. et al. Hadronic light-by-light scattering contribution to the muon anomalous magnetic moment from lattice QCD. Phys. Rev. Lett. 124, 132002 (2020).

    Article  ADS  Google Scholar 

  12. Chao, E.-H. et al. Hadronic light-by-light contribution to (g − 2)μ from lattice QCD: a complete calculation. Eur. Phys. J. C 81, 651 (2021).

    Article  ADS  Google Scholar 

  13. Giusti, D. et al. Electromagnetic and strong isospin-breaking corrections to the muon g − 2 from lattice QCD+QED. Phys. Rev. D 99, 114502 (2019).

    Article  ADS  Google Scholar 

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Correspondence to Christoph Lehner.

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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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