Leading hadronic contribution to the muon magnetic moment from lattice QCD

Borsanyi, Sz. and Fodor, Z. and Guenther, J. N. and Hoelbling, C. and Katz, S. D. and Lellouch, L. and Lippert, T. and Miura, K. and Parato, L. and Szabo, K. K. and Stokes, F. and Toth, B. C. and Torok, Cs. and Varnhorst, L. (2021) Leading hadronic contribution to the muon magnetic moment from lattice QCD. NATURE, 593 (7857). 51-+. ISSN 0028-0836, 1476-4687

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Abstract

The standard model of particle physics describes the vast majority of experiments and observations involving elementary particles. Any deviation from its predictions would be a sign of new, fundamental physics. One long-standing discrepancy concerns the anomalous magnetic moment of the muon, a measure of the magnetic field surrounding that particle. Standard-model predictions(1) exhibit disagreement with measurements(2) that is tightly scattered around 3.7 standard deviations. Today, theoretical and measurement errors are comparable; however, ongoing and planned experiments aim to reduce the measurement error by a factor of four. Theoretically, the dominant source of error is the leading-order hadronic vacuum polarization (LO-HVP) contribution. For the upcoming measurements, it is essential to evaluate the prediction for this contribution with independent methods and to reduce its uncertainties. The most precise, model-independent determinations so far rely on dispersive techniques, combined with measurements of the cross-section of electron-positron annihilation into hadrons(3-6). To eliminate our reliance on these experiments, here we use ab initio quantum chromodynamics (QCD) and quantum electrodynamics simulations to compute the LO-HVP contribution. We reach sufficient precision to discriminate between the measurement of the anomalous magnetic moment of the muon and the predictions of dispersive methods. Our result favours the experimentally measured value over those obtained using the dispersion relation. Moreover, the methods used and developed in this work will enable further increased precision as more powerful computers become available.

Item Type: Article
Uncontrolled Keywords: VACUUM-POLARIZATION CONTRIBUTION; FINITE-VOLUME; G-2;
Subjects: 500 Science > 530 Physics
Divisions: Physics > Institute of Theroretical Physics
Depositing User: Dr. Gernot Deinzer
Date Deposited: 21 Sep 2022 09:48
Last Modified: 21 Sep 2022 09:48
URI: https://pred.uni-regensburg.de/id/eprint/47838

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