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arXiv · 2606.24189

Rare Radiative Decays of Z boson into S- and P-wave Charmonium within the Bethe-Salpeter Model

Asif Ali·Yi-Jie Li·Guang-Zhi Xu·Kui-Yong Liu
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Abstract

We employ the Bethe-Salpeter (BS) model to investigate radiative decays of the Z boson into charmonium. Within the instantaneous approximation of the BS equation, we analyze the relevant decay channels for S-wave charmonium states ($\psi(nS)$, $\eta_{c}(nS)$, $n=1,2,3$) and P-wave charmonium states ($\chi_{c0}(mP)$, $\chi_{c1}(mP)$, $h_{c}(mP)$, $m=1,2$). We compute all branching fractions using leading-order Feynman diagrams. For the $J/\psi$ channel, our BS calculations suggest that prior theoretical results were likely underestimated, making our prediction more promising for future experimental measurements.

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Asif Ali, Yi-Jie Li, Guang-Zhi Xu, Kui-Yong Liu. 2026-06-23. Rare Radiative Decays of Z boson into S- and P-wave Charmonium within the Bethe-Salpeter Model. https://arxiv.org/abs/2606.24189

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