论文标题
$π^0 \ rightarrow e^+ e^的晶格QCD计算
Lattice QCD calculation of $π^0\rightarrow e^+ e^-$ decay
论文作者
论文摘要
我们将晶格QCD的应用扩展到两光子介导的订单$α^2 $稀有衰减$π^0 \ rightarrow e^+ e^ - $。通过结合Minkowski和Euclidean空间方法，我们能够直接从基础理论（QCD和QED）中计算出描述此衰减的复杂幅度，该理论（QCD和QED）预测了这种衰变。考虑了领先的连接和断开图；评估了连续性极限，并估计系统错误。我们找到$ \ mathrm {re} \ mathcal {a} = 18.60（1.19）（1.04）\，$ ev，$ \ mathrm {im} \ mathcal {a} = 32.59（1.50）（1.50）（1.50）（1.65）（1.65）\，$ ev，$ ev，$ $ $ $ $ \ frac {RE \ Mathcal {a}} {\ Mathrm {Im} \ Mathcal {a}} = 0.571（10）（4）$，以及部分宽度$γ（π^0 \toγγ）= 6.60（0.61）（0.67）（0.67）\，$ ev的结果。在这里，第一个错误是统计和第二系统。该计算是确定更具挑战性的两光子介导的衰减幅度的第一步，该衰减幅度有助于稀有衰减$ k \toμ^+μ^ - $。
We extend the application of lattice QCD to the two-photon-mediated, order $α^2$ rare decay $π^0\rightarrow e^+ e^-$. By combining Minkowski- and Euclidean-space methods we are able to calculate the complex amplitude describing this decay directly from the underlying theories (QCD and QED) which predict this decay. The leading connected and disconnected diagrams are considered; a continuum limit is evaluated and the systematic errors are estimated. We find $\mathrm{Re} \mathcal{A} = 18.60(1.19)(1.04)\,$eV, $\mathrm{Im} \mathcal{A} = 32.59(1.50)(1.65)\,$eV, a more accurate value for the ratio $\frac{\mathrm{Re} \mathcal{A}}{\mathrm{Im} \mathcal{A}}=0.571(10)(4)$ and a result for the partial width $Γ(π^0\toγγ) = 6.60(0.61)(0.67)\,$eV. Here the first errors are statistical and the second systematic. This calculation is the first step in determining the more challenging, two-photon-mediated decay amplitude that contributes to the rare decay $K\toμ^+μ^-$.
