Event calendar file
Studies of discrete symmetries in a purely leptonic system
Collaboration
J-PET
Abstract content
The $C$, $CP$, $T$ and $CPT$ symmetries are of fundamental importance in physics. Violation of $T$ or $CP$ invariance in purely leptonic systems have never been seen so far. Based on known mechanisms of $C$ and $CP$ violations, one cannot explain the large asymmetry between matter and antimatter in the observable Universe. Positronium is the lightest purely leptonic object decaying into photons. As an atom bound by a central potential, it is a parity eigenstate, and as an atom built out of an electron and an anti-electron, it is an eigenstate of the charge conjugation operator. Therefore, the positronium is a unique laboratory to study discrete symmetries whose precision is limited, in principle, by the effects due to the weak interactions expected at the level of $10^{-14}$ and photon–photon interactions expected at the level of $10^{-9}$. The newly constructed J-PET detector enables to perform tests of discrete symmetries in the leptonic sector via the determination of the expectation values of the discrete-symmetries-odd operators, which may be constructed from the spin of ortho-positronium atom and the momenta and polarization vectors of photons originating from its annihilation. We will present the potential of the J-PET detector to test the $C$, $CP$, $T$ and $CPT$ symmetries in the decays of positronium atoms. With respect to the previous experiments performed with crystal based detectors, J-PET built of plastic scintillators, provides superior time resolution, higher granularity, lower pile-ups, and opportunity of determining photon’s polarization. These features allow us to expect a significant improvement in tests of discrete symmetries in decays of positronium atom (a purely leptonic system).
J-PET: P. Moskal et al., Acta Phys.Polon. B47 (2016) 509.
J-PET: A. Gajos et al., Nucl. Instrum. Meth. A819 (2016) 54.
J-PET: D. Kamińska et al., Nukleonika 60 (2015) 729.
J-PET: P. Moskal et al., Nucl. Instrum. Meth. A775 (2015) 54.
J-PET: P. Moskal et al., Nucl. Instrum. Meth. A764 (2014) 317.
J-PET: P. Moskal, D. Alfs, T. Bednarski, P. Białas, E. Czerwiński, A. Gajos, B. Głowacz, D. Kamińska, A. Khreptak, G. Korcyl, T. Kozik, N. Krawczyk, E. Kubicz, M. Mohammed, Sz. Niedźwiecki, M. Pawlik-Niedźwiecka, Z. Rudy, M. Silarski, A. Wieczorek, M. Zieliński (Jagiellonian U., Cracow), C. Curceanu (LNF Frascati) M. Gorgol, B. Jasińska, B. Zgardzińska (Maria Curie U., Lublin), B.C. Hiesmayr (Vienna U.), P. Kowalski, W. Krzemień, L. Raczyński, W. Wiślicki, (NCBJ, Swierk)
