标题： μ子(g-2)实验的历史 显示英文标题

标题： The History of the Muon (g-2) Experiments

摘要： 我讨论μ子$(g-2)$测量的历史，从哥伦比亚-内维斯测量开始，该测量观察到了μ子衰变中的宇称不守恒，并首次测量了μ子$g$-因子，发现$g_\mu=2$。理论（标准模型）值包含了量子电动力学、通过强相互作用的强子真空极化和强子光子-光子环的贡献，以及来自$W$、$Z$和希格斯玻色子的弱电贡献。随后的实验，首先在内维斯，然后在欧洲核子研究中心以更高的精度进行，将μ子异常$a_\mu = (g_\mu-2)/2$测量到7.3百万分之一（ppm）的精度。布鲁克海文国家实验室的E821实验将精度提高到0.54 ppm，并首次观察到了弱电贡献。有趣的是，布鲁克海文测得的$a_\mu$值似乎比标准模型值大超过三个标准差。一项新的实验，费米国家加速器实验室E989，旨在将精度提高四倍，以明确这一结果是新物理通过环状过程出现的预兆，还是由于某些实验、统计或系统性问题。 显示英文摘要

摘要： I discuss the history of the muon $(g-2)$ measurements, beginning with the Columbia-Nevis measurement that observed parity violation in muon decay, and also measured the muon $g$-factor for the first time, finding $g_\mu=2$. The theoretical (Standard Model) value contains contributions from quantum electrodynamics, the strong interaction through hadronic vacuum polarization and hadronic light-by-light loops, as well as the electroweak contributions from the $W$, $Z$ and Higgs bosons. The subsequent experiments, first at Nevis and then with increasing precision at CERN, measured the muon anomaly $a_\mu = (g_\mu-2)/2$ down to a precision of 7.3 parts per million (ppm) The Brookhaven National Laboratory experiment E821 increased the precision to 0.54 ppm, and observed for the first time the electroweak contributions. Interestingly, the value of $a_\mu$ measured at Brookhaven appears to be larger than the Standard Model value by greater than three standard deviations. A new experiment, Fermilab E989, aims to improve on the precision by a factor of four, to clarify whether this result is a harbinger of new physics entering through loops, or from some experimental, statistical or systematic issue.