近日，德国约翰内斯古登堡美因茨大学Julian Parrino团队实现了利用格点QCD量子色动力学计算μ子（g − 2）中强子真空极化的紫外有限电磁修正。2025年7月17日出版的《高能物理杂志》发表了这项成果。
为了使强子真空极化（HVP）对μ介子(g - 2)μ异常磁矩的贡献精度达到0.2%，使完全标准模型预测的精度与直接实验测量相匹配，关键是要在HVP中包含超前的O（α）电磁修正。
在这项工作中，研究组从由内部光子和胶子连接的两个两点夸克环组成的图中确定了对后者的重要贡献。这种紫外有限校正是由晶格QCD计算出来的，它采用了一种坐标空间形式，其中光子在连续体和无限体积中被处理。他们的结果相当于（- 0.89±0.18）%对(g - 2)μ的领先级HVP贡献的修正。
为了克服大距离下日益恶化的统计噪声，他们的分析与质量低于1 GeV的轻伪标量介子的现象学模型相结合。特别是，他们的数据显示了一个非常陡峭的质量依赖，由带电的介子环决定。同样地，在内部光子连接两个单独的夸克环的HVP的O（α）修正中出现的其他图也是紫外有限的，可以用相同的形式来计算。
附：英文原文
Title: Computing the UV-finite electromagnetic corrections to the hadronic vacuum polarization in the muon (g 2) from lattice QCD
Author: Parrino, Julian, Biloshytskyi, Volodymyr, Chao, En-Hung, Meyer, Harvey B., Pascalutsa, Vladimir
Issue&Volume: 2025-07-17
Abstract: In order to reach a precision of 0.2% on the hadronic vacuum polarization (HVP) contribution to the anomalous magnetic moment of the muon, (g – 2)μ, such that the full Standard-Model prediction matches in precision the direct experimental measurement, it is crucial to include the leading, O(α) electromagnetic corrections to HVP. In this work, we determine an important contribution to the latter from a diagram comprised of two two-point quark-loops, connected by the internal photon and gluons. This ultraviolet-finite correction is calculated from lattice QCD using a coordinate-space formalism, where photons are treated in the continuum and infinite volume. Our result amounts to a (0.89 ± 0.18)% correction to the leading-order HVP contribution to (g – 2)μ. To overcome the worsening statistical noise at large distances, our analysis is combined with phenomenological models featuring light pseudoscalar mesons with masses below 1 GeV. In particular, our data show a very steep mass dependence as dictated by the charged pion loop. Similarly, the other diagrams appearing in the O(α)-corrections to the HVP with the internal photon connecting two separate quark loops are also ultraviolet-finite and can be computed with the same formalism.
DOI: 10.1007/JHEP07(2025)201
Source: https://link.springer.com/article/10.1007/JHEP07(2025)201