arXiv subjects

Yehan Xu

Publications and source records attributed to Yehan Xu.

2 recordsLinked to original sources

arXiv2026

Radiative charmonium decays in a contact-interaction model with dynamical quark anomalous magnetic moment

The BESIII Collaboration has recently reported two measurements of the two-photon decay width of the $\eta_c$ 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 $\eta_c\to\gamma\gamma$ and $J/\psi\to\gamma\eta_c$ 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 $\eta_c\to\gamma\gamma$ lies above the range that could be accommodated by the present framework, whereas the 2026 result is naturally consistent with it.

hep-ph↗

arXiv2024

Contact interaction treatment of $\mathcal{V}\to\mathcal{P}γ$ for light-quark mesons

The $\mathcal{V}\to\mathcal{P}γ$ and $η(η^\prime) \to γγ$ decays are evaluated within a Dyson-Schwinger and Bethe-Salpeter equations framework (here $\mathcal{V}=\{ρ^{\pm},K^{\star\pm},ϕ\}$ and $\mathcal{P}=\{π^{\pm},K^{\pm},η,η^{\prime}\}$). The so-called impulse approximation (IA) is employed in the computation of the decay constants involved and decay widths, and so in the estimation of the associated charge and interaction radii. For their part, the required propagators and vertices stem from a contact interaction model, embedded within a beyond rainbow-ladder (RL) truncation that accounts for the typical ladder exchanges, quark anomalous magnetic moment, as well as the non-Abelian anomaly. While the examined transitions produce decay widths plainly compatible with the available experimental data, those processes involving the $η-η'$ mesons highlight the incompleteness of the IA when considering beyond RL effects in the interaction kernels.

hep-ph↗