https://doi.org/10.1051/epjconf/201919905027
The tests of CP and CPT symmetry using the J-PET detector
for the J-PET Collaboration
1 Institute of Physics, Jagiellonian University, ul. Łojasiewicza 11, 30-348 Cracow, Poland
2 Department of Physics, College of Education for Pure Sciences, University of Mosul, Mosul, Iraq
* e-mail: muhsin.m@doctoral.uj.edu.pl
Published online: 1 February 2019
Symmetries under the parity transformation (P), charge-conjugation (C) and time reversal (T) are of fundamental importance in nuclear and elementary particle physics. Studies of the observables violating the combined CP symmetry constitute precise tests of the Standard Model. However, CP violation was observed to date only for systems involving quarks, raising the importance of searches its manifestations e.g. in purely leptonic systems. The 3γ decay of spin-aligned ortho-positronium atoms (o-Ps) can be used to test CP invariance in such a purely leptonic system. The Jagiellonian Positron Emission Tomograph (J-PET) detection system enables experimental tests of CP and CPT through measurement of the expectation values of angular correlation operators odd under these transformations and constructed from (i) spin vector of the ortho-positronium atom, (ii) co-planar momentum vectors of photons originating from the decay of the positronium atom, and (iii) linear polarization direction of annihilation photons. Precise experimental symmetry tests with J-PET are possible thanks to a dedicated reconstruction technique of 3γ ortho-positronium decays and a positronium production chamber including a highly porous aerogel target, whose setup allows for determining the orthopositronium spin polarization without the use of an external magnetic field.
© The Authors, published by EDP Sciences, 2019
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
