We present results for the charged kaon-box contributions to the hadronic light-by-light (HLBL) correction of the muon’s anomalous magnetic moment. To this end we determine the kaon electromagnetic form factor within the functional approach to QCD using Dyson-Schwinger and Bethe-Salpeter equations and evaluate the kaon-box contribution as defined in the dispersive approach to HLBL. As an update to previous work we also reevaluate the charged pion-box contribution taking effects due to isospin breaking into account. Our results are $a_{\mu }^{{\pi }^{\pm }-\mathrm{box}}=-15.7(2)(3)\times {10}^{-11}$ and $a_{\mu }^{K^{\pm }-\mathrm{box}}=-0.48(2)(4)\times {10}^{-11}$ thus confirming the large suppression of box contributions beyond the leading pion box.

• Received 13 November 2019
• Accepted 23 February 2020

DOI:https://doi.org/10.1103/PhysRevD.101.054015

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Published by the American Physical Society