Precision measurement of Hyperfine Splitting of Positronium using the Zeeman transition

为了检验过去的测量结果与QED预言之间的差异，我们测量了正电子素的基态超精细分裂。在该测量中，正电子素的定时信息用于分析。磁场的均匀性和稳定性也得到了很好的控制，得到的结果为203.3942 ± 0.0016（stat.）±- 0.0013（系统）GHz。这一结果有利于QED预测在1.2个标准偏差，并不利于以前的实验平均值的2.6个标准偏差。同时还发现，在精密测量中，电子偶素热化过程的影响是不可忽略的。

The ground state hyperfine splitting of positronium is newly measured to check the discrepancy between the past measurements and the QED prediction. In this measurement, the timing information of positronium is used for the analysis. The uniformity and the stability of the magnetic field is also well-controlled.The obtained result is 203.3942+-0.0016(stat.)+-0.0013(sys.)GHz. This result favors the QED prediction within 1.2 standard deviations, and disfavors the previous experimental average by 2.6 standard deviations. It is also found that the effect of the thermalization process of positronium cannot be negligible in the precision measurement.