## Original research papers

ASYMMETRY IN EXPERIMENTS TESTING CPT IN ORTHO-PS DECAY

Nevenka M. Antović, Sergey K. Andrukhovich

Pages: 177-182

Received: 28 FEB 2016, Received revised: 24 APR 2016, Accepted: 29 APR 2016, Published online: 26 DEC 2016

Atom of positronium (Ps) – the bound state of an electron and a positron, has two ground states: singlet (para-Ps) and triplet (ortho-Ps). In this paper we consider asymmetry in the CPT test experiments performed using polarized ortho-Ps decay. Ortho-Ps annihilates dominantly into three gamma rays with the continuous energy spectrum in the range (0-511) keV. In searching for decays of ortho-Ps which violate CPT symmetry, the correlation $\overrightarrow{S}*(\overrightarrow{k_{1}}x\overrightarrow{k_{2}})$ was tested, where $\underset{S}{\rightarrow}$ is the ortho-Ps spin, and , are the momenta of the two most energetic annihilation photons (Eg1Eg2Eg3). The experimental tests consisted in comparing the number of asymmetric decays of polarized ortho-Ps in two identical reflection-symmetric geometries, and the angular correlation coefficient was calculated from the asymmetry (A). Using our previous results, as well as the results of the other researchers, we particularly discuss the tests carried out at the three and seven-detector system (A = 0.0017 ± 0.0017 and A = 0.0008 ± 0.00091, respectively), together with their measuring errors.
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