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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2504.13789 |
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Table of Contents:
- The $τ$ spectral functions are an alternative to $e^+e^-$ cross-sections, where different measurements are not consistent, for computing the hadronic vacuum contribution to the muon magnetic anomaly $a_μ$. This requires a control of isospin-breaking effects which have to be corrected for. So far these corrections have been evaluated using theoretical models. In this letter, a new approach based only on data is presented for the determination of the most critical correction relating the $e^+e^-$ and $τ$ pion form factors. An updated evaluation of the total isospin-breaking correction is given and its impact is discussed in the context of $e^+e^-$-based $a_μ$ predictions and of the direct measurement.