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arXiv 2007.12106hep-phhep-ex
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如何揭示三个或更多五夸克态的本质？

How to reveal the nature of three or more pentaquark states?

C. W. Xiao, J. X. Lu, J. J. Wu, L. S. Geng

备注：
Updated with more comments, and welcome to comment
发表信息：
Phys. Rev. D 102, 056018 (2020)
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摘要：

在手征么正方法下，在重夸克自旋对称性的约束下，我们研究了${\bar D}^{(*)}Σ_c^{(*)}$通道的耦合通道相互作用，在其阈值附近，LHCb合作组已经报道了三个类五夸克${\bar D}^{(*)}Σ_c^{(*)}$态.在目前的工作中，我们考虑到π交换的贡献，通过箱图的相互作用势，从而解除质量的${\bar D}^*Σ_c^{(*)}$自旋多重态的简并。通过对$Λ_b^0 \to J/ψK^- p$衰变过程中$J/ψp$不变质量分布的拟合，我们发现LHCb五夸克态不能在$Λ_b^0$衰变过程中直接产生，而只能在$Λ_b^0$衰变产物${\bar D}^*Σ_c^{(*)}$的末态相互作用中间接产生，这进一步支持了LHCb五夸克态是$\bar{D}Σ_c$分子的性质.根据拟合结果，我们研究了部分衰变宽度/分支比的其他衰变通道，$\bar{D}^* Λ_c$，$\bar{D} Λ_c$，和$η_c N$，和相应的不变质量分布。与$J^P=\frac{1}{2}^-$、$P_c(4312)$、$P_c(4440)$以及$\bar{D}^* Σ_c^*$在4500 MeV附近的共振具有大的部分衰减宽度到$η_c N$，因此，可以在$η_c N$不变质量分布中容易地看到。相比之下，具有$J^P=\frac{3}{2}^-$、$P_c(4457)$、（预测的）窄$P_c(4380)$和具有约4520 MeV质量的$\bar{D}^* Σ_c^*$的束缚态的状态不衰变成$η_c N$。因此，$η_c N$通道应在未来进行研究，以进一步了解这些状态的性质，特别是$P_c(4440)$和$P_c(4457)$。

英文摘要：

Within the chiral unitary approach and with the constraints of heavy quark spin symmetry, we study the coupled channel interactions of ${\bar D}^{(*)}Σ_c^{(*)}$ channels, close to whose thresholds three pentaquark-like $P_c$ states have been reported by the LHCb Collaboration. In the present work, we take into account the contributions of pion exchanges via box diagrams to the interaction potentials, and therefore lift the degeneracy in the masses of ${\bar D}^*Σ_c^{(*)}$ spin multiplets. Fitting the $J/ψp$ invariant mass distributions in the $Λ_b^0 \to J/ψK^- p$ decay, we find that the LHCb pentaquark states can not be reproduced in the direct $J/ψp$ production in the $Λ_b^0$ decay, and can only be indirectly produced in the final state interactions of the $Λ_b^0$ decay products, ${\bar D}^*Σ_c^{(*)}$, which further supports the nature of these states as $\bar{D}Σ_c$ molecules. Based on the fit results obtained, we study the partial decay widths/branching ratios to other decay channels, $\bar{D}^* Λ_c$, $\bar{D} Λ_c$, and $η_c N$, and the corresponding invariant mass distributions. The resonances with $J^P=\frac{1}{2}^-$, $P_c(4312)$, $P_c(4440)$ and the one of $\bar{D}^* Σ_c^*$ around 4500 MeV, have large partial decay width into $η_c N$, and thus, can be easily seen in the $η_c N$ invariant mass distributions. By contrast, the states with $J^P=\frac{3}{2}^-$, $P_c(4457)$, the (predicted) narrow $P_c(4380)$ and the bound state of $\bar{D}^* Σ_c^*$ with a mass of about 4520 MeV, do not decay into $η_c N$. Therefore, the $η_c N$ channel should be studied in future to provide further insights into the nature of these states, especially that of the $P_c(4440)$ and $P_c(4457)$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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