Developing Analysis Criteria for Charge–Parity Symmetry Studies Using Photons From Ortho-Positronium Annihilation and Compton Scattering

The main aim of this research is to test the charge–parity discrete symmetry in the ortho-positronium (o-Ps) atom decay using the modular Jagiellonian positron emission tomography (J-PET) detector. The J-PET is distinguished by its ability to determine the polarization plane of photons emitted during positronium annihilation. The J-PET detector can investigate discrete symmetry by examining the non-zero expectation values of the symmetry-odd operators constructed from the momentum and direction of polarization plane of gamma (γ) quanta coming from o-Ps annihilation. In positronium decay, the photon–photon interactions in the final state due to vacuum polarization may mimic a charge–parity symmetry violation at the level of 10-9, according to the Standard Model prediction. Currently, with the help of the 192-strip J-PET detector, the experimental limits on charge–parity symmetry violation in o-Ps decay are set at a precision value of 0.0005 ± 0.0007. Using the modular J-PET detector, we aim to improve this value by at least an order of magnitude. This article focuses on developing analysis criteria towards improving the sensitivity level for charge–parity-discrete symmetry studies in o-Ps decay using the modular J-PET detector.