论文标题
通过旋转可观察力研究三角奇异性
Studying triangle singularity through spin observables
论文作者
论文摘要
在这项工作中，我们研究了衰减$ j/ψ\ rightarrowηπ$ $ ϕ $的旋转密度矩阵元素$ρ_{00} $。在先前的研究中，Besiii合作报告了Dalitz图中$π^0 ϕ $分布的1.4 GEV的频段。这种结构可能是由于共振或三角奇异性机制的产生引起的。我们发现，根据这些机制，最终$ ϕ $的自旋密度矩阵元素的预测显示出不同的特征。因此，在此反应中$ ϕ $的自旋密度矩阵元素的测量可能提供了一种研究三角奇异性并阐明反应机理的替代方法，即共振产生或运动效应。这项工作还显示了自旋可观察物在研究运动学奇点中的潜力。
In this work, we study the spin density matrix element $ρ_{00}$ of the $ϕ$ in the decay $J/ψ\rightarrow ηπϕ$. In previous studies, a band around 1.4 GeV on the $π^0ϕ$ distribution in Dalitz plot was reported by the BESIII Collaboration. This structure may be caused by the production of a resonance or the triangle singularity mechanism. We find that the predictions of the spin density matrix elements of the final $ϕ$ based on these mechanisms show distinct features. Thus the measurement of the spin density matrix elements of the $ϕ$ in this reaction may offer an alternative way to study the triangle singularity and to clarify the reaction mechanisms, i.e. resonance production or kinematic effects. This work also shows the potential of spin observables in studying kinematic singularities.
