论文标题
双$ j/ψ$频谱中的第三个峰结构
The third peak structure in the double $J/ψ$ spectrum
论文作者
论文摘要
最近，CMS和ATLAS合作报告分别报道了他们的$ J/ψJ/ψ$和$ J/ψψ^\ prime $不变质量分布，以搜索完全迷人的Tetraquarks。他们俩都报告了峰值结构的存在左右$ 7.2〜 \ gev $。在本文中，我们通过研究$ j/sthj/ψ$和$ j/ψj/ψ$和$ j/ψψ^\ prime $不变质量分布的$η_c（2s）η_c（2s）$通道的角色与背景贡献不一致。所有这些框架可以很好地描述实验数据，但是使用不同的极结构。例如，在这些结构的$ 2^{++} $描述的情况下，总是有一个极点低于$ j/ψj/ψ$阈值的极点。对于$ 0^{++} $ case，也可以在$ j/ψj/ψ$阈值下方找到类似的极点，但是质量要低得多。更重要的是，发现两极的数量是依赖病例的。对于$ 0^{++} $（$ 2^{++} $）的情况，由于$ 7.2〜 \ gev $ can（不能）的峰结构是由于$η_c（2s）η_c（2s）$ Channel的存在（不存在）而产生的。尽管极点位置取决于病例，但$ j/ψj/ψ$不变质量分布中的峰结构与$ j/ψψ^\ prime $不变质量分布左右$ 7.2〜 \ gev $之间的关系之间的关系是明确的。我们建议实验者详细扫描$ j/ψj/ψ$和$ j/ψψ^\ prime $不变的质量分布，尤其是$ 7.2〜 \ gev $，以探测第三个充满迷人状态的性质。
Recently, the CMS and ATLAS collaborations have reported their $J/ψJ/ψ$ and $J/ψψ^\prime$ invariant mass distributions, respectively, for searching for fully charmed tetraquarks. Both of them reported the existence of a peak structure around $7.2~\gev$. In this article, we exhibit the role of the $η_c(2S)η_c(2S)$ channel, which is close to this peak position, by studying the $J/ψJ/ψ$ and $J/ψψ^\prime$ invariant mass distributions for the potential quantum numbers $J^{PC}=0^{++}$ or $2^{++}$ by considering both the coherence and incoherence with the background contribution. All these frameworks can describe the experimental data very well, however with different pole structures. For instance, in the case of $2^{++}$ description of these structures, there always exists a pole slightly below the $J/ψJ/ψ$ threshold. For the $0^{++}$ case, a similar pole can also be found below the $J/ψJ/ψ$ threshold however with a much lower mass. More importantly, the number of the poles is found to be case-dependent. For the $0^{++}$ ($2^{++}$) case, the peak structure around $7.2~\gev$ can (cannot) be produced due to the presence (absence) of the $η_c(2S)η_c(2S)$ channel. Although the pole positions are case-dependent, the relation between the peak structure in the $J/ψJ/ψ$ invariant mass distribution and the dip structure in the $J/ψψ^\prime$ invariant mass distribution around $7.2~\gev$ is unambiguous. We suggest experimentalists to detailed scan both the $J/ψJ/ψ$ and the $J/ψψ^\prime$ invariant mass distributions, especially around $7.2~\gev$ to probe the nature of the third fully charmed state.
