Hadronic light by light corrections to the muon g-2: The Pion pole contribution
Hadronic light by light corrections to the muon g-2: The Pion pole contribution
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强子光对 μ 子 g-2 的光修正：π 极的贡献
DOI：
10.1103/physrevd.65.073034
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发表时间：
2001
影响因子：
5
通讯作者：
A. Nyffeler
中科院分区：
文献类型：
--
作者：
M. Knecht;A. Nyffeler
基于QCD的大nc和短距离特性，利用pi0-γ*-γ*跃迁形状因子的描述，考虑了从介子极贡献到强子光散射的介子反常磁矩的修正。通过首先使用Gegenbauer多项式的方法解析地执行角度积分，然后对欧几里得环动量的模数上剩余的二维积分进行数值计算，来处理所得到的双环积分。得到的值a_{u}(LbyL；pi0)=+5.8(1.0)x 10^{-10}，与最近的其他计算结果不一致。在矢量介子占优形状因子的情况下，按照同样的方法得到的结果为a_{u}(lbyL；pi0)_{vmd}=+5.6×10^{-10}，与前人得到的值仅有总体符号的差别。计入ETA和ETA-素极，三个赝标体态的总值a_{u}(LbyL；PS)=+8.3(1.2)x 10^{-10}。这一结果大大缩小了标准模型中a_{u}的实验值与其理论值之间的差异。
The correction to the muon anomalous magnetic moment from the pion-pole contribution to the hadronic light-by-light scattering is considered using a description of the pi0 - gamma* - gamma* transition form factor based on the large-Nc and short-distance properties of QCD. The resulting two-loop integrals are treated by first performing the angular integration analytically, using the method of Gegenbauer polynomials, followed by a numerical evaluation of the remaining two-dimensional integration over the moduli of the Euclidean loop momenta. The value obtained, a_{mu}(LbyL;pi0) = +5.8 (1.0) x 10^{-10}, disagrees with other recent calculations. In the case of the vector meson dominance form factor, the result obtained by following the same procedure reads a_{mu}(LbyL;pi0)_{VMD} = +5.6 x 10^{-10}, and differs only by its overall sign from the value obtained by previous authors. Inclusion of the eta and eta-prime poles gives a total value a_{mu}(LbyL;PS) = +8.3 (1.2) x 10^{-10} for the three pseudoscalar states. This result substantially reduces the difference between the experimental value of a_{mu} and its theoretical counterpart in the standard model.