Symmetry with regard to replacement of particles by antiparticles, mirror reflection, and time reversal is a fundamental theorem of quantum field theory. It has been confirmed for many processes, but in a system of charged leptons the precision of its testing remained rather low. This theorem is of particular interest for positronium atoms, because some anomalies have recently been observed in measuring the fine structure constant. P Moskal (Krakow University, Poland) and his co-authors have performed a new test of the CPT theorem in an experiment with orthopositronium [1]. Positrons were emitted by radioactive Na and produced orthopositronium in porous silica. Orthopositronium annihilation to three photons was analyzed and angular correlations between the original orbital angular momentum of orthopositronium and the annihilation plane determined by photon pulses were examined (provided that CPT invariance is conserved, correlations are absent up to very small radiation corrections). Photons were recorded by a detector consisting of plastic scintillator bands. Its high time resolution allowed observing photon triples using the coincidence method. At the level of 10ÿ4, no CPT symmetry violation was found, which improves more than threefold the accuracy of the CPT theorem test for the orthopositronium system.

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互联网上的物理新闻（基于电子预印本）

关于用反粒子、镜面反射和时间反转代替粒子的对称性是量子场论的基本定理。它已在许多过程中得到证实，但在带电轻子系统中，其测试的精度仍然相当低。这个定理对正电子原子特别感兴趣，因为最近在测量精细结构常数时观察到了一些异常现象。P Moskal（波兰克拉科夫大学）和他的合著者在正交电子鎓实验中对 CPT 定理进行了新的测试 [1]。正电子由放射性钠发射并在多孔二氧化硅中产生正电子。对三个光子的正电子湮没进行了分析，并检查了正电子原始轨道角动量与光子脉冲确定的湮没平面之间的角相关性（假设 CPT 不变性是守恒的，直到非常小的辐射校正都没有相关性）。光子由塑料闪烁带组成的探测器记录。它的高时间分辨率允许使用符合方法观察光子三元组。在 10ÿ4 水平，没有发现 CPT 对称性违反，这将正交电子系统的 CPT 定理测试的准确性提高了三倍以上。光子由塑料闪烁带组成的探测器记录。它的高时间分辨率允许使用符合方法观察光子三元组。在 10ÿ4 水平，没有发现 CPT 对称性违反，这将正交电子系统的 CPT 定理测试的准确性提高了三倍以上。光子由塑料闪烁带组成的探测器记录。它的高时间分辨率允许使用符合方法观察光子三元组。在 10ÿ4 水平，没有发现 CPT 对称性违反，这将正交电子系统的 CPT 定理测试的准确性提高了三倍以上。