Ablikim, M.Achasov, M. N.Adlarson, P.Aliberti, R.Amoroso, A.An, M. R.Çetin, Serkant Ali2024-05-192024-05-1920232470-00102470-0029https://doi.org10.1103/PhysRevD.108.L011101https://hdl.handle.net/20.500.12713/5837The Xi(0) asymmetry parameters are measured using entangled quantum Xi(0) - (Xi) over bar (0) pairs from a sample of (448.1 +/- 2.9) x 10(6) psi(3686) events collected with the BESIII detector at BEPCII. The relative phase between the transition amplitudes of the Xi(0)(Xi) over bar helicity states is measured to be Delta Phi = -0.050 +/- 0.150 +/- 0.020 rad, which implies that there is no obvious polarization at the current level of statistics. The decay parameters of the Xi(0) hyperon (alpha(Xi 0), alpha((Xi) over bar0), phi(Xi 0), phi((Xi) over bar0)) and the angular distribution parameter [alpha(psi(3686))] and Delta Phi are measured simultaneously for the first time. In addition, the CP asymmetry observables are determined to be A(CP)(Xi 0) = (alpha(Xi 0) + alpha((Xi) over bar0))/(alpha(Xi 0) - alpha((Xi) over bar0)) = -0.007 +/- 0.082 +/- 0.025 and Delta phi(Xi 0)(CP) = (phi(Xi 0) + phi((Xi) over bar0))/2 = -0.079 +/- 0.082 +/- 0.010 rad, which are consistent with CP conservation.eninfo:eu-repo/semantics/openAccessHyperonArticle1081WOS:0010632639000022-s2.0-85166419607N/A10.1103/PhysRevD.108.L011101Q1