Moskal P, Gajos A, Mohammed M, Chhokar J, Chug N, Curceanu C, Czerwiński E, Dadgar M, Dulski K, Gorgol M, Goworek J, Hiesmayr B C, Jasińska B, Kacprzak K, Kapłon Ł, Karimi H, Kisielewska D, Klimaszewski K, Korcyl G, Kowalski P, Krawczyk N, Krzemień W, Kozik T, Kubicz E, Niedźwiecki S, Parzych S, Pawlik-Niedźwiecka M, Raczyński L, Raj J, Sharma S, Choudhary S, Shopa R Y, Sienkiewicz A, Silarski M, Skurzok M, Stępień E Ł, Tayefi F, Wiślicki W
Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, S. Łojasiewicza 11, 30-348, Kraków, Poland.
Total-Body Jagiellonian-PET Laboratory, Jagiellonian University, Kraków, Poland.
Nat Commun. 2021 Sep 27;12(1):5658. doi: 10.1038/s41467-021-25905-9.
Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron-positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner to record ortho-positronium (o-Ps) annihilations with single-event estimation of o-Ps spin and determine the complete spectrum of an angular correlation operator sensitive to CPT-violating effects. We find no violation at the precision level of 10, with an over threefold improvement on the previous measurement.
在电荷、宇称和时间反演变换（CPT）联合作用下，带电轻子系统的对称性几乎未得到检验。尽管有严格的量子电动力学限制，但电子 - 正电子束缚态（正电子素原子）预测中的差异促使人们进一步开展研究，包括进行基本对称性测试。虽然CPT非不变性效应可能表现为末态光子与湮灭正电子素自旋之间存在非零角关联，但此前的测量受限于对后者的了解。在此，我们展示了断层扫描重建技术应用于正电子素原子的三光子湮灭，以在无磁场或极化正电子素源的情况下估计其自旋极化。我们使用基于塑料闪烁体的正电子发射断层扫描仪来记录正电子素（o-Ps）的湮灭，并对o-Ps自旋进行单事件估计，确定对CPT违反效应敏感的角关联算符的完整谱。我们发现在10的精度水平上没有违反情况，比之前的测量有超过三倍的改进。
