PoS - Proceedings of Science
Volume 430 - The 39th International Symposium on Lattice Field Theory (LATTICE2022) - QCD in searches for physics beyond the Standard Model
Chiral extrapolation of hadronic vacuum polarization and isospin-breaking corrections
M. Hoferichter*, G. Colangelo, B.L. Hoid, B. Kubis, J. Ruiz de Elvira, D. Stamen and P. Stoffer
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Pre-published on: November 07, 2022
Published on: April 06, 2023
By far the biggest contribution to hadronic vacuum polarization (HVP) arises from the two-pion channel. Its quark-mass dependence can be evaluated by combining dispersion relations with chiral perturbation theory, providing guidance on the functional form of chiral extrapolations, or even interpolations around the physical point. In addition, the approach allows one to estimate in a controlled way the isospin-breaking (IB) corrections that arise from the pion mass difference. As an application, we present an updated estimate of phenomenological expectations for electromagnetic and strong IB corrections to the HVP contribution to the anomalous magnetic moment of the muon. In particular, we include IB effects in the $\bar K K$ channel, which are enhanced due to the proximity of the $\bar K K$ threshold and the $\phi$ resonance. The resulting estimates make it unlikely that the current tension between lattice-QCD and data-driven evaluations of the HVP contribution is caused by IB corrections.
DOI: https://doi.org/10.22323/1.430.0316
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