$η_cη_c$ and $J/ψJ/ψ$ scatterings from lattice QCD
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2025
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| author | Li, Geng Shi, Chunjiang Chen, Ying Sun, Wei |
| author_facet | Li, Geng Shi, Chunjiang Chen, Ying Sun, Wei |
| contents | We investigate the $J^{PC}=(0,2)^{++}$ $η_c η_c$ and $J/ψJ/ψ$ scatterings in $N_f=2$ lattice QCD at two pion masses $m_π\approx 420$\,MeV and 250\,MeV. The quark field smearing scheme used in the distillation method strongly suppresses high-momentum states, thereby limiting the maximum accessible center-of-mass energy in this study to approximately 6.6\,GeV. Given the observed near-decoupling of the $η_cη_c$ and $J/ψJ/ψ$ channels, we analyze their scattering properties using the single-channel Lüscher's method. In $0^{++}$ channels, $η_cη_c$ and $J/ψJ/ψ$ have repulsive and attractive interactions, respectively, which are dominated by the quark exchange effects with the Fierz rearrangement determining the interaction characteristic. A likely $0^{++}$ virtual state is observed below the threshold by 20-40\,MeV in the ${}^1S_0$ $J/ψJ/ψ$ scattering and may have connection with $X(6200)$. In $2^{++}$ channels, the near-threshold interaction for the ${}^5S_2$ $J/ψJ/ψ$ scattering is repulsive. The di-charmonium interactions are found to be insensitive to $m_π$ and can be consistently understood in terms of quark rearrangement effects combined with a one-gluon-exchange mechanism, both of which are supported by our lattice QCD results. Most importantly, we observe a $2^{++}$ resonance in the ${}^5S_2$ $J/ψJ/ψ$ scattering, whose properties are $(m_R,Γ_R)=\big(6544(10),552(34)\big)$\,MeV for $m_π\approx 420$\,MeV and $\big(6539(13),546(57)\big)$\,MeV for $m_π\approx 250$\,MeV, which are compatible with the parameters of the fully-charmed broad structure $X(6600)$ (or $X(6400)$) reported by ATLAS and CMS. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2505_23220 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | $η_cη_c$ and $J/ψJ/ψ$ scatterings from lattice QCD Li, Geng Shi, Chunjiang Chen, Ying Sun, Wei High Energy Physics - Lattice We investigate the $J^{PC}=(0,2)^{++}$ $η_c η_c$ and $J/ψJ/ψ$ scatterings in $N_f=2$ lattice QCD at two pion masses $m_π\approx 420$\,MeV and 250\,MeV. The quark field smearing scheme used in the distillation method strongly suppresses high-momentum states, thereby limiting the maximum accessible center-of-mass energy in this study to approximately 6.6\,GeV. Given the observed near-decoupling of the $η_cη_c$ and $J/ψJ/ψ$ channels, we analyze their scattering properties using the single-channel Lüscher's method. In $0^{++}$ channels, $η_cη_c$ and $J/ψJ/ψ$ have repulsive and attractive interactions, respectively, which are dominated by the quark exchange effects with the Fierz rearrangement determining the interaction characteristic. A likely $0^{++}$ virtual state is observed below the threshold by 20-40\,MeV in the ${}^1S_0$ $J/ψJ/ψ$ scattering and may have connection with $X(6200)$. In $2^{++}$ channels, the near-threshold interaction for the ${}^5S_2$ $J/ψJ/ψ$ scattering is repulsive. The di-charmonium interactions are found to be insensitive to $m_π$ and can be consistently understood in terms of quark rearrangement effects combined with a one-gluon-exchange mechanism, both of which are supported by our lattice QCD results. Most importantly, we observe a $2^{++}$ resonance in the ${}^5S_2$ $J/ψJ/ψ$ scattering, whose properties are $(m_R,Γ_R)=\big(6544(10),552(34)\big)$\,MeV for $m_π\approx 420$\,MeV and $\big(6539(13),546(57)\big)$\,MeV for $m_π\approx 250$\,MeV, which are compatible with the parameters of the fully-charmed broad structure $X(6600)$ (or $X(6400)$) reported by ATLAS and CMS. |
| title | $η_cη_c$ and $J/ψJ/ψ$ scatterings from lattice QCD |
| topic | High Energy Physics - Lattice |
| url | https://arxiv.org/abs/2505.23220 |