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arXiv 2202.03124hep-phhep-latnucl-th
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用最近的晶格相移研究$ππ$散射

Scrutinizing $ππ$ scattering in light of recent lattice phase shifts

Xiu-Li Gao, Zhi-Hui Guo, Zhiguang Xiao, Zhi-Yong Zhou

摘要:

本文利用一种新的S矩阵色散解,即PKU表象,分析了格点QCD方法确定的$IJ=00, 11, 20$分波$ππ$散射相移,在这种色散解中,散射振幅自动满足么正性和解析性,相移可以方便地分解为割点和各种极点(包括束缚态)的贡献,虚拟状态和共振。用$SU(2)$手征微扰理论估计了左手剪切对$\mathcal{O}(p^4)$的贡献。Balanchandran-Nuyts-Roskies关系被认为是满足交叉对称性要求的约束。结果表明,在$m_π=391$ MeV处,由强子谱协作组(HSC)得到的$IJ=00$ $ππ$散射相移揭示了$σ$在低于$ππ$阈值时存在一个束缚态极点和一个虚态极点,而不是只有一个束缚态极点.为了再现在$m_π=391$ MeV的晶格相移,在$IJ=20$通道中的虚态极点被发现是必要的,以平衡从手征振幅的左手切效应。对HSC的$m_π=236$ MeV的晶格结果也进行了类似的讨论。观测到的极位置随π介子质量变化的行为可以为我们理解$σ$共振的动力学起源提供深刻的见解。

英文摘要:

In this paper, the $IJ=00, 11, 20$ partial wave $ππ$ scattering phase shifts determined by the lattice QCD approach are analyzed by using a novel dispersive solution of the S-matrix, i.e. the PKU representation, in which the unitarity and analyticity of scattering amplitudes are automatically satisfied and the phase shifts are conveniently decomposed into the contributions of the cuts and various poles, including bound states, virtual states and resonances. The contribution of the left-hand cut is estimated by the $SU(2)$ chiral perturbation theory to $\mathcal{O}(p^4)$. The Balanchandran-Nuyts-Roskies relations are considered as constraints to meet the requirements of the crossing symmetry. It is found that the $IJ=00$ $ππ$ scattering phase shifts obtained at $m_π=391$ MeV by Hadron Spectrum Collaboration (HSC) reveal the presence of both a bound state pole and a virtual state pole below the $ππ$ threshold rather than only one bound state pole for the $σ$. To reproduce the lattice phase shifts at $m_π=391$ MeV, a virtual-state pole in the $IJ=20$ channel is found to be necessary in order to balance the left-hand cut effects from the chiral amplitudes. Similar discussions are also carried out for the lattice results with $m_π=236$ MeV from HSC. The observed behaviors of the pole positions with respect to the variation of the pion masses can provide deep insights into our understanding of the dynamical origin of $σ$ resonance.

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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