Feasibility Study of the Time Reversal Symmetry Tests in Decay of Metastable Positronium Atoms with the J-PET Detector

Figure 2

Vectors describing the final state of an o-Ps→3 annihilation in the o-Ps frame of reference. denotes orthopositronium spin and are the momentum vectors of the annihilation photons, lying in a single plane. The operator defined in (4) is a measure of angular correlation between the positronium spin and the decay plane normal vector.