标题： Källén-Lehmann谱表示的标量SU(2)胶球 显示英文标题

标题： Källén-Lehmann Spectral Representation of the Scalar SU(2) Glueball

摘要： 提出了从规范不变的格点QCD两点关联函数估算Källén-Lehmann谱密度的方法，并通过适当的反演方法进行了探讨。作为概念验证，研究了量子数为$J^{PC} = 0^{++}$的SU(2)胶球谱在不同格点间距下的情况。利用arXiv:1910.07756发表的数据估算谱密度和胶球谱。我们对基态质量的估算与其中基于关联函数大时间指数行为的传统方法得出的结果非常一致。此外，谱密度还包含了谱中激发态的线索。 显示英文摘要

摘要： The estimation of the K\"all\'en-Lehmann spectral density from gauge invariant lattice QCD two point correlation functions is proposed, and explored via an appropriate inversion method. As proof of concept the SU(2) glueball spectrum for the quantum numbers $J^{PC} = 0^{++}$ is investigated for various values of the lattice spacing. The spectral density and the glueball spectrum are estimated using the published data of arXiv:1910.07756. Our estimates for the ground state mass are in good agreement with the traditional approach published therein, which is based on the large time exponential behaviour of the correlation functions. Furthermore, the spectral density also contains hints of excites states in the spectrum.