Improved analysis of double $J/ψ$ production in $Z$-boson decay
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arXiv
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| Format: | Preprint |
| Publié: |
2024
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| _version_ | 1866910463779930112 |
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| author | Wang, Guang-Yu Wu, Xing-Gang Zheng, Xu-Chang Yan, Jiang Zhang, Jia-Wei |
| author_facet | Wang, Guang-Yu Wu, Xing-Gang Zheng, Xu-Chang Yan, Jiang Zhang, Jia-Wei |
| contents | In this paper, we present an improved calculation for the decay rate of the rare $Z$-boson decay into $J/ψ+ J/ψ$. This decay is dominated by the photon fragmentation mechanism, i.e., the transition $Z\to J/ψ+ γ^{*}$ followed by the fragmentation $γ^{*}\to J/ψ$. In our calculation, the amplitude of $γ^{*}\to J/ψ$ is extracted from the measured value of $Γ(J/ψ\to e^+ e^-)$, and the amplitude of $Z\to J/ψ+ γ^{*}$ is calculate through the light-cone approach. The higher-order QCD and relativistic corrections in the amplitude of $γ^{*}\to J/ψ$ and the large logarithms of $m_{_Z}^2/m_c^2$ that appear in the amplitude of $Z\to J/ψ+ γ^{*}$ are resummed in our calculation. Besides, the non-fragmentation amplitude is calculated based on the NRQCD factorization, and the next-to-leading order QCD and relativistic corrections are included. The obtained branching fraction for this $Z$ decay channel is $8.66 ^{+1.48} _{-0.69}\times 10^{-11}$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_07777 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Improved analysis of double $J/ψ$ production in $Z$-boson decay Wang, Guang-Yu Wu, Xing-Gang Zheng, Xu-Chang Yan, Jiang Zhang, Jia-Wei High Energy Physics - Phenomenology In this paper, we present an improved calculation for the decay rate of the rare $Z$-boson decay into $J/ψ+ J/ψ$. This decay is dominated by the photon fragmentation mechanism, i.e., the transition $Z\to J/ψ+ γ^{*}$ followed by the fragmentation $γ^{*}\to J/ψ$. In our calculation, the amplitude of $γ^{*}\to J/ψ$ is extracted from the measured value of $Γ(J/ψ\to e^+ e^-)$, and the amplitude of $Z\to J/ψ+ γ^{*}$ is calculate through the light-cone approach. The higher-order QCD and relativistic corrections in the amplitude of $γ^{*}\to J/ψ$ and the large logarithms of $m_{_Z}^2/m_c^2$ that appear in the amplitude of $Z\to J/ψ+ γ^{*}$ are resummed in our calculation. Besides, the non-fragmentation amplitude is calculated based on the NRQCD factorization, and the next-to-leading order QCD and relativistic corrections are included. The obtained branching fraction for this $Z$ decay channel is $8.66 ^{+1.48} _{-0.69}\times 10^{-11}$. |
| title | Improved analysis of double $J/ψ$ production in $Z$-boson decay |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2404.07777 |