标题： 关于$Z_{cs}$的奇异结构 显示英文标题

标题： About the exotic structure of $Z_{cs}$

摘要： 最近在BESIII实验中观察到了围绕$3.98$GeV 的一种新的强子结构。 从其衰变模式来看，人们将其归类为奇特态是合理的，例如$Z^+_{cs}$，它是$Z_{c}(3900)$的奇异伙伴。 这一发现首次表明了在魅夸克区存在带有奇异夸克的奇特态，因此具有特殊的重要性。 通过QCD求和规则技术，我们分析了$Z^+_{cs}$的可能构型和物理性质，并发现它可能由两种结构$[1_c]_{\bar{c} u}\otimes[1_c]_{\bar{s} c}$和$[1_c]_{\bar{c} c}\otimes[1_c]_{\bar{s} u}$，或者$[3_c]_{\bar{c} u}\otimes[\bar{3}_c]_{\bar{s} c}$和$[3_c]_{\bar{c} c}\otimes[\bar{3}_c]_{\bar{s} u}$混合构成，带有$J^P=1^+$。 从物理角度看，这似乎表明每种构型中四种可能的电流的复合体出现，这说明单独的电流对强子谱学及其衰变性质的评估有时是不够的。 我们发现在这两种情况下，能量谱在不确定范围内可能与实验观测很好地吻合，即$3.98$GeV，但需要注意前者不被矢量介子交换模型所青睐。 各种$Z^+_{cs}(3980)$衰变模式被评估，这对于确定其结构并留待实验验证是至关重要的。 我们还预测了$Z^0_{cs}$的质量，它是$Z^+_{cs}(3980)$的中性伙伴，并分析了其主要的衰变概率。 显示英文摘要

摘要： Very recently a new hadronic structure around $3.98$ GeV was observed in BESIII experiment. From its decay modes, it is reasonable for people to assign it to the category of exotic state, say $Z^+_{cs}$, the stranged-parter of $Z_{c}(3900)$. This finding indicates for the first time the exotic state with strange quark in charm sector, and hence has a peculiar importance. By virtue of the QCD Sum Rule technique, we analyze the $Z^+_{cs}$ about its possible configuration and physical properties, and find it could be configured as a mixture of two types of structures, $[1_c]_{\bar{c} u}\otimes[1_c]_{\bar{s} c}$ and $[1_c]_{\bar{c} c}\otimes[1_c]_{\bar{s} u}$, or $[3_c]_{\bar{c} u}\otimes[\bar{3}_c]_{\bar{s} c}$ and $[3_c]_{\bar{c} c}\otimes[\bar{3}_c]_{\bar{s} u}$, with $J^P=1^+$. Physically, it then appears to be the emergence of a compound of four possible currents in each configuration, which tells the single current evaluation of hadron spectroscopy and their decay properties are sometimes not enough. We find in both cases the energy spectra may fit well with the experimental observation, i.e. $3.98$ GeV, within the uncertainties, while noted the former is not favored by vector meson exchange model. Various $Z^+_{cs}(3980)$ decay modes are evaluated, which are critical for pinning down its configuration and left for experimental verification. We also predict the mass of $Z^0_{cs}$, the neutral partner of $Z^+_{cs}(3980)$, and analyze its dominant decay probabilities.