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arXiv 1102.3715hep-lat
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随机矩阵的QCD符号问题及动力学模拟

The QCD sign problem and dynamical simulations of random matrices

Jacques Bloch, Tilo Wettig

摘要:

在非零夸克化学势下,由于费米子行列式的符号问题,QCD的动力学格点模拟受到阻碍。符号问题的严重性可以通过费米子行列式的平均相位来评估。在较早的文件中,我们推导出一个公式的微观极限的平均相位一般拓扑使用手征随机矩阵理论。在目前的文件中,我们提出了一个替代推导相同的数量,导致一个更简单的表达式,也是可计算的有限大小的矩阵,远离微观极限。我们明确证明了在微观极限下新旧结果的等价性。有限尺寸矩阵的结果说明了收敛到微观极限。我们比较的分析结果与动态随机矩阵模拟,其中各种重新加权的方法来规避的符号问题。我们讨论这些重新加权方法的利弊。

英文摘要:

At nonzero quark chemical potential dynamical lattice simulations of QCD are hindered by the sign problem caused by the complex fermion determinant. The severity of the sign problem can be assessed by the average phase of the fermion determinant. In an earlier paper we derived a formula for the microscopic limit of the average phase for general topology using chiral random matrix theory. In the current paper we present an alternative derivation of the same quantity, leading to a simpler expression which is also calculable for finite-sized matrices, away from the microscopic limit. We explicitly prove the equivalence of the old and new results in the microscopic limit. The results for finite-sized matrices illustrate the convergence towards the microscopic limit. We compare the analytical results with dynamical random matrix simulations, where various reweighting methods are used to circumvent the sign problem. We discuss the pros and cons of these reweighting methods.

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