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arXiv · 2207.04694

$1^{-+}$ Hybrid in $J/\psi$ Radiative Decays from Lattice QCD

Feiyu Chen·Xiangyu Jiang·Ying Chen·Ming Gong·Zhaofeng Liu·Chunjiang Shi·Wei Sun
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Abstract

We present the first theoretical prediction of the production rate of $1^{-+}$ light hybrid meson $\eta_1$ in $J/\psi$ radiative decays. In the $N_f=2$ lattice QCD formalism with the pion mass $m_\pi\approx 350$ MeV, the related electromagnetic multipole form factors are extracted from the three-point functions that involve necessarily quark annihilation diagrams, which are calculated through the distillation method. The partial width of $J/\psi\to \gamma \eta_1$ is determined to be $2.29(77)~\mathrm{eV}$ at the $\eta_1$ mass $m_{\eta_1}=2.23(4)$ GeV. If $\eta_1$ corresponds to the recently observed $\eta_1(1855)$ in the process $J/\psi\to \gamma\eta_1(1855)\to \gamma \eta\eta'$ by BESIII, then the branching fraction $\mathrm{Br}(J/\psi\to \gamma\eta_1(1855))$ is estimated to be $6.2(2.2)\times 10^{-5}$, which implies $\mathrm{Br}(\eta_1(1855)\to \eta\eta')\sim 4.3\%$.

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Feiyu Chen, Xiangyu Jiang, Ying Chen, Ming Gong, Zhaofeng Liu, Chunjiang Shi, Wei Sun. 2022-07-11. $1^{-+}$ Hybrid in $J/\psi$ Radiative Decays from Lattice QCD. https://doi.org/10.1103/physrevd.107.054511

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