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- Title
Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography.
- Authors
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.
- Abstract
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 10−4, with an over threefold improvement on the previous measurement. CPT violation could manifest itself in annihilating positronium events, but searching for this effect would require to know the spin of the annihilating system. Here, the authors do this using a positron-emission tomography scanner, finding no violation with a statistical precision of 10−4.
- Subjects
POSITRONIUM; TOMOGRAPHY; BOUND states; STATISTICAL accuracy; SYMMETRY; MAGNETIC fields
- Publication
Nature Communications, 2021, Vol 12, Issue 1, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-021-25905-9