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arXiv 1102.5544hep-lathep-ph
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双味格点量子色动力学中$π^0$的双光子衰变

Two-photon decay of $π^0$ from two-flavor lattice QCD

E. Shintani, S. Aoki, S. Hashimoto, T. Onogi, N. Yamada

备注：
A contribution to the XXVIII International Symposium on Lattice Field Theory, Lattice2010, June 14-19, 2010, Villasimius, Italy
发表信息：
PoS(Lattice 2010)159
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摘要：

研究了有限轻夸克质量对辐射$π^0$衰变宽度的修正。利用格点量子色动力学和重叠费米子公式，我们计算了（欧几里德）动量空间中$<PV_μV_ν>$形式的三点函数，它对应于$π^0\rightarrow γ^*γ^*$振幅。为了拟合格点数据，我们使用了两种不同的矢量介子优势（VMD）的修正。一种是VMD与次领先阶（NLO）手征微扰理论（ChPT）的组合形式，另一种是π介子环图的图解形式。我们提取了NLO ChPT中的一个低能常数，并估算了包括有限质量修正的$π^0\rightarrow γγ$衰变宽度。

英文摘要：

We study the correction to the radiative $π^0$ decay width due to finite light quark mass. Using lattice QCD with the overlap fermion formulation, we calculate the three-point function of the form $<PV_μV_ν>$ in the (Euclidean) momentum space, which corresponds to the $π^0\rightarrow γ^*γ^*$ amplitude. To fit the lattice data, we use two different modifications of vector meson dominance (VMD) ansatz. One is a combined form of VMD with the next-to-leading order (NLO) chiral perturbation theory (ChPT), and the other is a resummed form of pion-loop diagrams. We extract one of the low energy constants in NLO ChPT, and estimate $π^0\rightarrow γγ$ decay width including finite mass correction.

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