Neutral Pion Lifetime Measurements and the QCD Chiral Anomaly
Neutral Pion Lifetime Measurements and the QCD Chiral Anomaly
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中性π介子寿命测量和 QCD 手性异常
DOI：
10.1103/revmodphys.85.49
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发表时间：
2011
影响因子：
44.1
通讯作者：
B. Holstein
中科院分区：
文献类型：
--
作者：
A. Bernstein;B. Holstein
QCD的一个基本性质是手征反常的存在，这是$\pi ^0\rightarrow\gamma\gamma $衰变振幅的主要成分。基于这种异常和它的小（$\simeq $4.5%）手征修正，一个可靠的预测$\pi ^0 $寿命可以用来作为一个测试QCD在约束尺度的能量。本文回顾了介子从发现到现在的有趣的实验和理论历史。实验结果与理论预测一致，在当前（$\simeq $3%）的实验误差范围内;然而，它们还不够精确，无法测试手征校正结果，这是一个可靠的QCD预测，并且已知$\simeq $1%的不确定性。在这个层面上，存在着实验上的不一致，需要引起注意。建议今后可能的工作，以提高目前的精度。
A fundamental property of QCD is the presence of the chiral anomaly, which is the primary component of the $\pi^0\rightarrow\gamma\gamma$ decay amplitude. Based on this anomaly and its small ($\simeq$ 4.5%) chiral correction, a firm prediction of the $\pi^0$ lifetime can be used as a test of QCD at confinement scale energies. The interesting experimental and theoretical histories of the $\pi^0$ meson are reviewed, from discovery to the present era. Experimental results are in agreement with the theoretical prediction, within the current ($\simeq$ 3%) experimental error; however, they are not yet sufficiently precise to test the chiral corrected result, which is a firm QCD prediction and is known to $\simeq$ 1% uncertainty. At this level there exist experimental inconsistencies, which require attention. Possible future work to improve the present precision is suggested.