Briceño Raul A, Dudek Jozef J, Edwards Robert G, Wilson David J
Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, Virginia 23606, USA.
Department of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795, USA.
Phys Rev Lett. 2017 Jan 13;118(2):022002. doi: 10.1103/PhysRevLett.118.022002. Epub 2017 Jan 9.
We present for the first time a determination of the energy dependence of the isoscalar ππ elastic scattering phase shift within a first-principles numerical lattice approach to QCD. Hadronic correlation functions are computed including all required quark propagation diagrams, and from these the discrete spectrum of states in the finite volume defined by the lattice boundary is extracted. From the volume dependence of the spectrum, we obtain the S-wave phase shift up to the KK[over ¯] threshold. Calculations are performed at two values of the u, d quark mass corresponding to m_{π}=236,391 MeV, and the resulting amplitudes are described in terms of a σ meson which evolves from a bound state below the ππ threshold at the heavier quark mass to a broad resonance at the lighter quark mass.
我们首次展示了在 QCD 的第一性原理数值晶格方法中对等标量 ππ 弹性散射相移的能量依赖性的确定。计算了强子关联函数，包括所有所需的夸克传播图，并从这些图中提取由晶格边界定义的有限体积内的离散能谱。根据能谱的体积依赖性，我们得到了直至 KK[上划线]阈值的 S 波相移。计算是在对应于 m_π = 236,391 MeV 的 u、d 夸克质量的两个值下进行的，并且所得振幅用一个 σ 介子来描述，该 σ 介子从重夸克质量下低于 ππ 阈值的束缚态演变为轻夸克质量下的宽共振态。
