Speaker
Description
Search for violation of the symmetry under combined transformation of charge, parity and time reversal in charged leptonic sector can be tested through the non-vanishing expectation value of certain angular correlation operators that are odd under CPT transformation. In this talk we will discuss the experimental approach for a CPT symmetry test by measuring angular correlations between the spin and momenta of photons originating from ortho-positronium (o-Ps$\rightarrow$$3{\gamma}$) decays. This experiment is performed with the J-PET detector which measures a broad range of kinematical configurations of ortho-positronium annihilation into three photons and is the first experiment to determine the full range of the CPT-odd angular correlation. In the first part of the talk, we will present how a novel technique to estimate the spin of ortho-positronium and momenta of annihilation photons for single recorded ortho-positronium event allowed J-PET to measure the expectation value of CPT symmetry odd angular correlation operator at the precision level of 10$^{-4}$, a factor of three better than the best known previous experimental result. The second part of talk will focus on the new measures and perspectives for J-PET in improving the sensitivity to CPT violating effects beyond the level of 10$^{-4}$ by increasing the efficiency for detection of photons from ortho-positronium decays by means of using a new 24 Modular J-PET detector and spherical annihilation chamber.
