The positronium (Ps) atom, a bound state of an electron and a positron, is a fascinating system for fundamental physics research. Its properties, well-described by Quantum Electrodynamics (QED) within the Standard Model (SM), make it an ideal candidate for precise tests. The J- PET setup at Jagiellonian University, based on plastic scintillator detectors with high angular and timing resolutions, enables multidisciplinary studies including tests of symmetries, quantum entanglement, and the search for Dark Matter through positronium decays.

This work focuses on current searches for Dark Matter (DM) involving ortho-Positronium (o-Ps) decays using the J-PET detector. The primary goal is to investigate Mirror Matter, a proposed type of matter that could restore parity invariance and serve as a potential DM candidate. This study aims to achieve unprecedented precision in measuring the o-Ps decay to three gamma quanta, comparing results to QED predictions in the search for elusive DM.