Extracting the chiral anomaly from $e^+e^-\to 3π$
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866909678230831104 |
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| author | Hoferichter, Martin Hoid, Bai-Long Kubis, Bastian |
| author_facet | Hoferichter, Martin Hoid, Bai-Long Kubis, Bastian |
| contents | The strength of the interaction of three pions and a photon, $F_{3π}$ is predicted by the axial anomaly in terms of the pion decay constant, a relation that is frequently used to constrain low-energy radiative processes involving pions, but only tested experimentally at the $10\%$ level. Here, we present a new avenue to test this prediction, via a fit of a dispersive description of the $γ^*\to3π$ amplitude to data for $e^+e^-\to 3π$. From the global fit to SND, CMD-2, and BaBar data we obtain $F_{3π}=33.1(1.7)\,\text{GeV}^{-3}$, in agreement with the chiral prediction at the level of $5\%$. We also consider dispersive fits to the recent data by Belle II, in which case we observe tensions with the dispersive constraints, the width parameters of $ω$ and $ϕ$, and the chiral anomaly. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_13827 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Extracting the chiral anomaly from $e^+e^-\to 3π$ Hoferichter, Martin Hoid, Bai-Long Kubis, Bastian High Energy Physics - Phenomenology High Energy Physics - Experiment High Energy Physics - Lattice Nuclear Theory The strength of the interaction of three pions and a photon, $F_{3π}$ is predicted by the axial anomaly in terms of the pion decay constant, a relation that is frequently used to constrain low-energy radiative processes involving pions, but only tested experimentally at the $10\%$ level. Here, we present a new avenue to test this prediction, via a fit of a dispersive description of the $γ^*\to3π$ amplitude to data for $e^+e^-\to 3π$. From the global fit to SND, CMD-2, and BaBar data we obtain $F_{3π}=33.1(1.7)\,\text{GeV}^{-3}$, in agreement with the chiral prediction at the level of $5\%$. We also consider dispersive fits to the recent data by Belle II, in which case we observe tensions with the dispersive constraints, the width parameters of $ω$ and $ϕ$, and the chiral anomaly. |
| title | Extracting the chiral anomaly from $e^+e^-\to 3π$ |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment High Energy Physics - Lattice Nuclear Theory |
| url | https://arxiv.org/abs/2504.13827 |