Radiative charmonium decays in a contact-interaction model with dynamical quark anomalous magnetic moment
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arXiv
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| Hauptverfasser: | , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866918472913518592 |
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| author | Xu, Yehan Xing, Zanbin Raya, Khépani Chang, Lei |
| author_facet | Xu, Yehan Xing, Zanbin Raya, Khépani Chang, Lei |
| contents | The BESIII Collaboration has recently reported two measurements of the two-photon decay width of the $η_c$ meson. The 2024 result is significantly larger than most theoretical and empirical expectations, while a subsequent measurement published in early 2026 shows better agreement with the world average and conventional theoretical estimates. In this work, we study the $η_c\toγγ$ and $J/ψ\toγη_c$ processes within a contact interaction model that incorporates valence-quark anomalous magnetic moment effects, which are absent in standard treatments. Besides achieving agreement with modern lattice QCD estimates for these observables, we find that the 2024 central value for $η_c\toγγ$ lies above the range that could be accommodated by the present framework, whereas the 2026 result is naturally consistent with it. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_26185 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Radiative charmonium decays in a contact-interaction model with dynamical quark anomalous magnetic moment Xu, Yehan Xing, Zanbin Raya, Khépani Chang, Lei High Energy Physics - Phenomenology The BESIII Collaboration has recently reported two measurements of the two-photon decay width of the $η_c$ meson. The 2024 result is significantly larger than most theoretical and empirical expectations, while a subsequent measurement published in early 2026 shows better agreement with the world average and conventional theoretical estimates. In this work, we study the $η_c\toγγ$ and $J/ψ\toγη_c$ processes within a contact interaction model that incorporates valence-quark anomalous magnetic moment effects, which are absent in standard treatments. Besides achieving agreement with modern lattice QCD estimates for these observables, we find that the 2024 central value for $η_c\toγγ$ lies above the range that could be accommodated by the present framework, whereas the 2026 result is naturally consistent with it. |
| title | Radiative charmonium decays in a contact-interaction model with dynamical quark anomalous magnetic moment |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2604.26185 |