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arXiv 2105.04563hep-phhep-exhep-latnucl-th
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改进的$π^0\to e^+e^-$标准模型预测

Improved Standard-Model prediction for $π^0\to e^+e^-$

Martin Hoferichter, Bai-Long Hoid, Bastian Kubis, Jan Lüdtke

摘要:

本文提出了一种改进的中性π介子双轻子衰变的标准模型预言。环路振幅由$π^0\toγ^*γ^*$的π跃迁形状因子决定,为此我们采用了一种色散表示法,该表示法结合了类空间和类时间数据以及短距离约束。由此产生的SM分支分数,$\text{BR}[π^0\to e^+e^-]=6.25(3)\times 10^{-8}$,锐化物理超越SM的约束,包括赝标量和轴向矢量介质。

英文摘要:

We present an improved Standard-Model (SM) prediction for the dilepton decay of the neutral pion. The loop amplitude is determined by the pion transition form factor for $π^0\toγ^*γ^*$, for which we employ a dispersive representation that incorporates both space-like and time-like data as well as short-distance constraints. The resulting SM branching fraction, $\text{BR}[π^0\to e^+e^-]=6.25(3)\times 10^{-8}$ , sharpens constraints on physics beyond the SM, including pseudoscalar and axial-vector mediators.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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