论文标题
X（6900）的两光子衰变来自LHC的光线散射
The two-photon decay of X(6900) from light-by-light scattering at the LHC
论文作者
论文摘要
LHCB的合作最近发现了双$ j/ψ$质量分布的6.9 GEV的结构，这可能是第一个完全融合的Tetraquark State $ x（6900）$。基于媒介 - 梅森优势（VMD），该状态应具有显着的分支比，以衰减两个光子。我们表明，逐光散射的记录的LHC数据确实可以适应这种状态，其$γγ$分支比为$ 10^{ - 4} $的订单分支比，甚至比VMD推断的值大。旋转 - 帕特分配$ 0^{ - +} $与VMD预测的一致性比$ 0^{++} $更好地达成一致，尽管在当前精度下并不明显。该区域中的进一步光散射数据应在运行3中阐明该状态的性质，并且可能在LHC的高光度阶段（运行4等）获得。
The LHCb Collaboration has recently discovered a structure around 6.9 GeV in the double-$J/ψ$ mass distribution, possibly a first fully-charmed tetraquark state $X(6900)$. Based on vector-meson dominance (VMD) such a state should have a significant branching ratio for decaying into two photons. We show that the recorded LHC data for the light-by-light scattering may indeed accommodate for such a state, with a $γγ$ branching ratio of order of $10^{-4}$, which is larger even than the value inferred by the VMD. The spin-parity assignment $0^{-+}$ is in better agreement with the VMD prediction than $0^{++}$, albeit not significantly at the current precision. Further light-by-light scattering data in this region, clarifying the nature of this state, should be obtained in the Run 3 and probably in the high-luminosity phase of the LHC (Run 4 etc.).
