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

Abstract

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.