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arXiv 2206.00545hep-latcond-mat.stat-mech
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二维强耦合QCD的Grassmann高阶张量重整化群方法

Grassmann higher-order tensor renormalization group approach for two-dimensional strong-coupling QCD

Jacques Bloch, Robert Lohmayer

摘要:

本文提出了一种张量网络方法,研究了具有非零化学势的交错夸克的二维强耦合QCD。在对无限耦合的规范场进行积分后,配分函数可以写成由耦合的局域数值张量和格拉斯曼张量组成的张量网络的完全收缩。为了评估配分函数和计算观测量,我们开发了一个格拉斯曼高阶张量重整化群方法,专门为这个模型量身定制。在粗化过程中,相邻格拉斯曼张量的阻塞是解析执行的,张量网络中格拉斯曼变量的总数在每个粗化步骤中减少了两倍。粗站点的数值张量截断使用高阶奇异值分解。通过比较用张量方法计算的配分函数、手征凝聚和重子密度与小晶格上精确解析结果的差异,验证了该方法的有效性,最大体积为$4\times4$。对于较大的体积,我们提出了第一张量的手征凝聚体的质量和体积的函数的结果,并观察到,手征对称性不打破动态在两个维度。我们还提出了张量结果的数量密度作为化学势的函数,这暗示在一级相变。

英文摘要:

We present a tensor-network approach for two-dimensional strong-coupling QCD with staggered quarks at nonzero chemical potential. After integrating out the gauge fields at infinite coupling, the partition function can be written as a full contraction of a tensor network consisting of coupled local numeric and Grassmann tensors. To evaluate the partition function and to compute observables, we develop a Grassmann higher-order tensor renormalization group method, specifically tailored for this model. During the coarsening procedure, the blocking of adjacent Grassmann tensors is performed analytically, and the total number of Grassmann variables in the tensor network is reduced by a factor of two at each coarsening step. The coarse-site numeric tensors are truncated using higher-order singular value decompositions. The method is validated by comparing the partition function, the chiral condensate and the baryon density computed with the tensor method with exact analytical results on small lattices up to volumes of $4\times4$. For larger volumes, we present first tensor results for the chiral condensate as a function of the mass and volume, and observe that the chiral symmetry is not broken dynamically in two dimensions. We also present tensor results for the number density as a function of the chemical potential, which hint at a first-order phase transition.

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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