The theoretical uncertainty of $(g-2)_μ$ is currently dominated by hadronic contributions. In order to express those in terms of directly measurable quantities, we consider a sum rule relating $g-2$ to an integral of a photo-absorption cross section. The sum rule, attributed to Schwinger, can be viewed as a combination of two older sum rules: Gerasimov-Drell-Hearn and Burkhardt-Cottingham. The Schwinger sum rule has an important feature, distinguishing it from the other two: the relation between the anomalous magnetic moment and the integral of a photo-absorption cross section is linear, rather than quadratic. The linear property makes it suitable for a straightforward assessment of the hadronic contributions to $(g-2)_μ$. From the sum rule we rederive the Schwinger $α/2π$ correction, as well as the formula for the hadronic vacuum-polarization contribution. As an example of the light-by-light contribution we consider the single-meson exchange.
Quantum simulation of real-time current correlators and DIS-inspired observables in the Schwinger model
University of Massachusetts Boston（马萨诸塞大学波士顿分校）；Stony Brook University（石溪大学）；University of California, Los Angeles（加州大学洛杉矶分校）；Brookhaven National Laboratory（布鲁克海文国家实验室）；Central China Normal University（华中师范大学）；Universidade de Santiago de Compostela（圣地亚哥德孔波斯特拉大学）
Hadronic vacuum polarization contribution to $a_μ$ from functional methods with strong and electromagnetic isospin breaking
University of Valencia and CSIC（瓦伦西亚大学和中科院）；Universidad de Huelva（韦尔瓦大学）；Universidad Autónoma de Querétaro（克雷塔罗自治大学）；Justus-Liebig-Universität Gießen（吉森大学）；GSI Helmholtzzentrum für Schwerionenforschung（亥姆霍兹重离子研究中心）；Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional（国立理工学院高级研究中心）
