Vector correlators in lattice QCD: Methods and applications
Vector correlators in lattice QCD: Methods and applications
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DOI：
10.1140/epja/i2011-11148-6
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发表时间：
2011-11-01
影响因子：
2.7
通讯作者：
Meyer, Harvey B.
中科院分区：
文献类型：
--
作者：
Bernecker, David;Meyer, Harvey B.
讨论了格点QCD中主导强子真空极化的计算。利用e（+）e（-）->强子截面的汇编实验数据的优良质量，我们预测了物理π质量下的大体积晶格计算的结果，并设计了晶格的计算策略，以影响重要的唯象量，例如对（g - 2）（mu）的主要强子贡献和电磁耦合常数的运行。首先，R（s）比可以直接在阈值区域的晶格上计算，并且我们提供了在扭曲边界条件下这样做的公式。其次，当前相关器投影到零空间动量，在欧几里得时间间隔，它可以被准确地计算，提供了一个潜在的关键测试的实验R（s）比在该区域是最相关的（g - 2）（μ）。这个观察也可以反过来：在中等距离的矢量相关器可以用来确定fm中的晶格间距，我们在这个方向上提出了一个具体的建议。最后，我们量化的有限尺寸效应的电流相关器来自低能量的2 π态，并提供了一个一般的参数化的真空极化环面。
We discuss the calculation of the leading hadronic vacuum polarization in lattice QCD. Exploiting the excellent quality of the compiled experimental data for the e(+)e(-) -> hadrons cross-section, we predict the outcome of large-volume lattice calculations at the physical pion mass, and design computational strategies for the lattice to have an impact on important phenomenological quantities such as the leading hadronic contribution to (g - 2)(mu) and the running of the electromagnetic coupling constant. First, the R(s) ratio can be calculated directly on the lattice in the threshold region, and we provide the formulae to do so with twisted boundary conditions. Second, the current correlator projected onto zero spatial momentum, in a Euclidean time interval where it can be calculated accurately, provides a potentially critical test of the experimental R(s) ratio in the region that is most relevant for (g - 2)(mu). This observation can also be turned around: the vector correlator at intermediate distances can be used to determine the lattice spacing in fm, and we make a concrete proposal in this direction. Finally, we quantify the finite-size effects on the current correlator coming from low-energy two-pion states and provide a general parametrization of the vacuum polarization on the torus.